Wooldridge, M. and Jennings, N.R. (1995). Agent theories, architectures, and languages: a survey. In: (Wooldridge and Jennings, 1995), pp.

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1 9 Discussion More more organisations offer a 24 hour a day telephone service using a call centre to coordinate the service provided. Without support to really support clients, by, for example, being able to schedule appointments with a client, such a service is of limited value: only simple questions can be answered. This paper has presented a multi-agent system, introduced to increase the value of 24 hour a day service by supporting call centres in making appointments scheduling activities of Employees in preparation of such an appointment. The multi-agent system architecture described in this paper is based on a principled design, using the compositional development method for multi-agent systems DESIRE. To schedule procedures in which more than one Employee is involved, the scheduling task is modelled as a distributed effort: each Employee is represented by its own Personal Assistant agent (that also maintains the Employee's agenda), a Work Manager agent co-ordinates the schedules of the Personal Assistant agents, the client through the call centre. The basis of our approach is Jennings' co-operation model (Jennings, 1995) for projects based on joint intentions, formalised in (Brazier, Jonker Treur, 1997), applied to project co-ordination in (Brazier, Jonker Treur, 1996). This multi-agent system architecture has been applied to the banking domain, in co-operation with ( partially funded by) the Rabo Bank. References Brazier, F.M.T., Dunin-Keplicz, B., Jennings, N.R. Treur, J. (1995). Formal specification of Multi-Agent Systems: a real-world case. In: V. Lesser (Ed.), Proc. of the First International Conference on Multi-Agent Systems, ICMAS 95, MIT Press, Cambridge, MA, pp Extended version in: International Journal of Cooperative Information Systems, M. Huhns, M. Singh, (Eds.), special issue on Formal Methods in Cooperative Information Systems: Multi-Agent Systems, vol. 6, 1997, pp Brazier, F.M.T., C.M. Jonker, J. Treur (1996). Modelling Project Coordination in a Multi- Agent Framework. In: Proceedings of the Fifth Workshops on Enabling Technology for Colloborative Enterprises, WET ICE'96, IEEE Computer Society Press, 1996, pp Brazier, F.M.T., Jonker, C.M., Treur, J. (1997). Formalisation of a cooperation model based on joint intentions. In: (Müller, Wooldridge Jennings, 1997), pp Jennings, N.R. (1995). Controlling Cooperative Problem Solving in Industrial Multi-Agent Systems using Joint Intentions, Artificial Intelligence Journal 74 (2), pp Müller, J.P., M.J. Wooldridge, N.R. Jennings (eds.) (1997). Intelligent Agents III (Proc. of the Third International Workshop on Agent Theories, Architectures Languages, ATAL'96), Lecture Notes in AI, volume 1193, Springer Verlag, 1997 Wooldridge, M. Jennings, N.R. (1995). Agent theories, architectures, languages: a survey. In: (Wooldridge Jennings, 1995), pp Wooldridge, M. Jennings, N.R. (1995). Intelligent Agents (Proc. of the First International Workshop on Agent Theories, Architectures Languages, ATAL'94), Lecture Notes in Artificial Intelligence, Vol. 890, Springer Verlag, Berlin. 576

2 (After finishing the schedule for the second client request, WM will need to reschedule activities acquire_info-1 check_client-1.) The agent WM next tries to schedule activity test_credentials-2. This activity can only be performed by employee1. Thus WM communicates to PA1: PA1 replies: commitment_request(activity(test_credentials-2), duration(8), es(6), lf(14)). commitment_condition(activity(test_credentials-2), duration(8), es(6), ef(14), activity(authorize_student_loan-1)). Similarly, activity authorize_credit_card-2 is accepted by PA1. The agent WM selects a set of possible appointments communicates commitments requests for these appointments to both Personal Assistants. commitment_request(activity(appointment-2a), duration(1), es(17), lf(18)). commitment_request(activity(appointment-2b), duration(1), es(18), lf(19)). commitment_request(activity(appointment-2c), duration(1), es(19), lf(20)). Both Personal Assistants commit to all appointments, WM rejects the commitments of PA2. The agent WM reports to the Call Centre Agent that it can hle the second request proposes the following options for an appointment: proposed_appointment(c2, service(credit_card), 17). proposed_appointment(c2, service(credit_card), 18). proposed_appointment(c2, service(credit_card), 19). The Call Centre Agent responds with: accepted_appointment(c2, service(credit_card), 17). WM cancels the remaining two options. Finally, activities acquire_info-1, check_client-1 authorize_student_loan-1 all need to be rescheduled. The details of this negotiation process have been omitted for brevity. WM accepts confirms all new commitments. Leading to the following final schedules of the Employee: Employee 1 Employee 2 time 0-4 acquire_info-2 time 0-2 other engagements time 4-6 free time time 2-6 check_client-2 time 6-14 test_credentials-2 time 6-10 acquire_info-1 time authorize_credit_card-2 time check_client-1 time appointment-2a time authorize_student_loan-1 time appointment-1b Note that as the procedure student_loan_proc from the first request is completed at time 20 the procedure credit_card_proc from the second request is completed at time 17 the appointment proposed for the first procedure can still proceed. 575

3 8.2 The next appointment: rescheduling Next, the Call Centre Agent communicates a new request: appointment_request(c2, service(credit_card), urgency(high), priority(high)). Determination of the WM goal the selection of the procedure are dealt with in the same way as described in the previous section. The following rule describes the procedure selected to service the request of client c2. if then selected_procedure(credit_card_proc) selected_activity(activity(acquire_info), duration(4)) selected_activity(activity(check_client), duration(4)) selected_activity(activity(test_credentials), duration(8)) selected_activity(activity(authorize_credit_card), duration(3)) selected_activity(activity(appointment), duration(1)) precedence(activity(acquire_info), activity(test_credentials), finish_start) precedence(activity(check_client), activity(test_credentials), finish_start) precedence(activity(test_credentials), activity(authorize_credit_card), finish_start) precedence(activity(authorize_credit_card), activity(appointment), finish_start) ultimate_deadline(deadline(18)); As for the first client request, capabilitiesare checked to see which Personal Assistants can be asked to commit to which activities. Again, this information is requested from the component maintain agent information, resulting in the same knowledge about capabilities as previously reported: the Employee represented by PA1 is capable of performing all activities, the Employee represented by PA2 is capable of performing all activities except activity test_credentials. This means that it is important that employee1 is scheduled to perform activity test_credentials-2. The WM notes that activity acquire_info-2 check_client-2 must be performed in the same time slot, otherwise the procedure cannot be completed on time. WM therefore communicates the following requests to the Personal Assistants: To PA1: To PA2: commitment_request(activity(acquire_info-2), duration(4), es(0), lf(7)). commitment_request(activity(check_client-2), duration(4), es(0), lf(7)). To which they reply: PA1: PA2: commitment_condition(activity(acquire_info-2), duration(4), es(0), ef(4), activity(acquire_info-1)). commitment_condition(activity(check_client-2), duration(4), es(2), ef(6), activity(check_client-1)). These replies state that both PA1 PA2 can commit to the request if the WM can retract the activity mentioned in the last argument (the activities acquire_info-1 check_client-1). As the current procedure is more important than the previous one, the WM accepts ( it does so by not sending a commitment reject to the Personal Assistants). The schedules of the Employees are now the following: Employee 1 Employee 2 time 0-4 acquire_info-2 time 0-2 other engagements time 4-6 free time time 2-6 check_client-2 time 6-12 time authorize_student_loan-1 appointment-1b 574

4 commitment_reply(activity(appointment-1a), duration(1), es(20), ef(21)). commitment_reply(activity(appointment-1c), duration(1), es(22), ef(23)). WM rejects the commitment of PA2 for appointment-1a. WM favoured the commitment of PA1 because PA1 committed to most activities needed for client in question. The WM reports to the Call Centre Agent that it can hle the request proposes the following possible appointments: proposed_appointment(c1, service(student_loan), 20). proposed_appointment(c1, service(student_loan), 21). proposed_appointment(c1, service(student_loan), 22). Note that the deadline of the selected procedure was 20. The Call Centre Agent responds with: accepted_appointment(c1, service(student_loan), 21). Once the selected appointment has been communicated to WM, the reserved time for the appointments that were not selected can be cancelled. Thus WM communicates a rejection for appointment-1a to PA1: commitment_reject(activity(appointment-1a)). a rejection for appointment-1c to PA2: commitment_reject(activity(appointment-1c)). Finally, WM confirms all commitments that have not been rejected: To PA1: commitment_confirm(activity(acquire_info-1), duration(4), es(0), lf(6)). commitment_confirm(activity(authorize_student_loan-1), duration(6), es(6), lf(12)). commitment_ confirm(activity(appointment-1a), duration(1), es(20), ef(21)). commitment_ confirm(activity(appointment-1b), duration(1), es(21), ef(22)). To PA2: commitment_confirm(activity(check_client-1), duration(4), es(2), lf(6)). commitment_ confirm(activity(appointment-1c), duration(1), es(22), ef(23)). Note that the latest finish of activity acquire_info-1 is updated to 6, as employee2 will have just finished activity check_client-1 by time 6. This means that employee1 has some extra time to complete activity acquire_info-1. This is the reason commitment confirmation is postponed in the current model. In general, although each activity is scheduled for a specific time slot in the agenda of one of the Employees, some slack may exist for some of the activities (they can be finished later). The latest finish time is contained within the confirmation of the commitment therefore communicated to the Personal Assistant that might use the slack for later rescheduling. The schedules of employee1 employee2 are as follows: Employee 1 Employee 2 time 0-4 acquire_info-1 time 0-2 other engagements time 4-6 free time time 2-6 check_client-1 time 6-12 time authorize_student_loan-1 appointment-1b 573

5 not_available(from(0), to(2)). Thus, CM determines that PA2 s Employee can accept the request of the WM, but that it can only start at time 2. Thus PA2 replies: commitment_reply(activity(acquire_info-1), duration(4), es(2), ef(6)). The agent WM receives both commitment replies decides it likes the reply from PA1 best as its Employee can start before the Employee of PA2. Thus WM communicates a rejection to PA2: commitment_reject(activity(acquire_info-1)). Confirmation of the commitment of PA1 is postponed until the schedule is complete. The explanation for this is postponed as well. The WM now tries to acquire a commitment for the second activity, communicates to both Personal Assistants: commitment_request(activity(check_client-1), duration(4), es(0), lf(14)). To which agent PA1 replies: commitment_reply(activity(check_client-1), duration(4), es(4), ef(8)). as it has a commitment for activity acquire_info-1 for time 0 to 4. Agent PA2 replies: commitment_reply(activity(check_client-1), duration(4), es(2), ef(6)). The agent WM rejects the commitment of PA1 in the same way as it rejected the commitment of PA2 for activity acquire_info-1. WM also asks for commitments for activity authorize_student_loan-1 (derived by WM s component CM): PA1 answers commitment_request(activity(authorize_student_loan-1), duration(6), es(6), lf(20)). commitment_reply(activity(authorize_student_loan-1), duration(6), es(6), ef(12)). PA2 answers: commitment_reply(activity(authorize_student_loan-1), duration(6), es(6), ef(12)). WM chooses PA1, rejects the commitment of PA2. Finally, WM requests commitments for activity appointment-1 at several time points (20, 21, 22), by requesting appointments with three different labels: commitment_request(activity(appointment-1a), duration(1), es(20), lf(21)). commitment_request(activity(appointment-1b), duration(1), es(21), lf(22)). commitment_request(activity(appointment-1c), duration(1), es(22), lf(23)). As the request is not that important ( more important requests may be received in the future) the agent WM plans the possible appointments some time after the latest finish of its last activity (authorize_student_loan-1) scheduled.. Note that the deadline of the selected procedure was 20. PA1 responds with: commitment_reply(activity(appointment-1a), duration(1), es(20), ef(21)). commitment_reply(activity(appointment-1b), duration(1), es(21), ef(22)). PA2 answers: 572

6 if then selected_procedure(student_proc) selected_activity(activity(acquire_info), duration(4)) selected_activity(activity(check_client), duration(4)) selected_activity(activity(authorize_student_loan), duration(6)) selected_activity(activity(appointment), duration(1)) precedence(activity(acquire_info), activity(authorize_student_loan), finish_start) precedence(activity(check_client), activity(authorize_student_loan), finish_start) precedence(activity(authorize_student_loan), activity(appointment), finish_start) ultimate_deadline(deadline(20)); The ultimate deadline specifies when all activities of the procedure, with the exception of the appointment, should be completed. Capabilities must be checked to see which Personal Assistants can be asked to perform which activities. This information is requested from the component maintain agent information: request(capabilities_of(pa1)). request(capabilities_of(pa2)). These requests result in the following knowledge about capabilities: capability_of(pa1, activity(acquire_info)). capability_of(pa1, activity(check_client)). capability_of(pa1, activity(test_credentials)). capability_of(pa1, activity(authorize_credit_card)). capability_of(pa1, activity(authorize_student_loan)). capability_of(pa1, activity(appointment)). capability_of(pa2, activity(acquire_info)). capability_of(pa2, activity(check_client)). capability_of(pa2, activity(authorize_credit_card)). capability_of(pa2, activity(appointment)). This information basically states that the Employee represented by PA1 is capable of performing all activities, the Employee represented by PA2 is capable of performing all activities except activity test_credentials. All of this information is transported to component generate modify project recipe ( another component of CM). There, the selected activities are instantiated commitment requests are generated sent out to the Personal Assistants. It computes the earliest starts (es) latest finishes (lf) of the activities to be scheduled: earliest start latest finish acquire_info check_client authorize_student_loan appointment Instantiations are denoted by the number in the name communicates a commitment request to PA1 PA2: of the activity. The agent WM commitment_request(activity(acquire_info-1), duration(4), es(0), lf(14)). These requests are communicated to the Personal Assistants which transfer them to their own CM components. PA1 looks at the empty agenda of employee1 decides that employee1 can perform the activity. Personal Assistant PA1 reports the best it can do, given the earliest start commitment_reply(activity(acquire_info-1), duration(4), es(0), ef(4)). I.e., given that the earliest start is time 0 the duration is 4, the earliest finish (ef) is 4. PA2 has received the following information from employee2: 571

7 8 Description of an example process A trace of the multi-agent system is described in this section. It focuses on the agents within one local bank. The agents in this example are: the Call Centre (CC) Agent with the goal to make an appointment for a Client currently on the telephone. the Work Manager (WM) of the local bank by which the Client needs to be helped. The WM distributes work among the Employees monitors the execution of the activities. two Personal Assistants (PA1 PA2), whom each represent an Employee. They make commitments for the Employee they represent, when s/he is not present or unable to decide for him/herself. two Employees (EM1 EM2). The following sections describe a trace of the multi-agent system. Communication between agents always goes through the agent interaction management component, as described earlier. Incoming communication is interpreted by agent interaction management, from there, distributed to the relevant components. Also outgoing information is prepared in agent interaction management. For the sake of explanation, the agent interaction management components, a number of administrative steps information elements have been excluded from the trace. 8.1 Making an appointment The agent CC communicates a request to the agent WM of a selected local bank for an appointment concerning a certain service. appointment_request(c1, service(student_loan), urgency(high), priority(low)). Agent CC requests an appointment for client c1 concerning a student loan, which has a high urgency for the client but a low priority to the bank. A goal is derived from this request by the WM represented within the OPC. goal(arrange_appointment(c1, service(student_loan), urgency(high), priority(low))). The component determine goals commitments determines whether or not the WM will make this goal its own. The following rule is one of the rules that determines this. if then goal(arrange_appointment(c: Clients, S: Services, U: Urgencies, priority(low))) projected_work_load(low) own_goal(arrange_appointment(c: Clients, S: Services, U: Urgencies, priority(low))); The projected work load is determined by the amount of work already planned. This information is maintained in the component maintenance of agent information. Once the goal is accepted by the agent WM, it is transferred to the component CM. The component prepare project commitments first selects a procedure that achieves the goal. A procedure includes a generic description of the activities that need to be performed to achieve a certain goal. The following rule is one of the rules specified for this purpose. if then own_goal(arrange_appointment(c: Clients, service(student_loan), U: Urgencies, priority(low))) selected_procedure(student_proc); The selection of the procedure defines the activities that need to be performed: 570

8 communicated to the Personal Assistant. In addition, the Employee can make changes to the Employee profile maintained by the Personal Assistant. Agenda Monday, November 3 Tuesday, November 4 Wensday, November Preparing mortgage contract for Mrs. Robinson Check Mr. Pepper Acquire information on Mrs. Martelli Lunch Lunch Lunch Check Mr. Pepper Acquire information on Mrs. Martelli Check Mrs. Martelli Thurs day, November 6 Friday, November 7 your profile Check Mrs. Martelli Lunch Authorize student loan for Mrs. Martelli Authorize student loan for Mrs. Martelli Lunch Appointment with Mrs. Robinson for her mortgage Figure 7 Interface to Employee next week previous week month overview help By double clicking on an agenda item more information becomes available. For example, by double clicking on the item Monday, November 3, a new window pops up displaying the deadline for the activity, the priority, the latest possible starting time, which other Employee will provide the necessary information, the client s identification (e.g., bank account number). The item in the bottom right rectangle can also be opened. For example, by clicking on the item your profile the window in Figure 8 pops up. Employee profile Capabilities: business loan contract morgage contract client appointments Preferences Between : only activities of type S Rather not activities of type X No appointments with Mr. Brute Authorizations: Signing of contracts up to Level 2 Access to information up to level 2 Figure 8 Employee profile The Employee profile can be modified by pull-down menus. For example, the Employee can choose from a stard list of capabilities of bank Employees. 569

9 not to accept a request as a goal for the Personal Assistant (see the Work Manager for further explanation). If a request is accepted, the request information is transferred to component cooperation management. The component cooperation management is composed of two components generate project monitor project. The component generate project itself is also composed of two components: the component prepare project commitments the component generate modify project recipe. The component monitor project also has two components: the component assess viability the component determine consequences. An initial request is forwarded to generate project, together with an existing schedule from the component maintenance of world information. The component prepare project commitments determines whether or not the Employee the Personal Assistant represents is capable of performing the activity, the component generate modify schedule determines whether a new schedule can be generated in which the requested commitment can be awarded. If a new schedule can be generated, this schedule is forwarded to the component monitor project. The component monitor project uses information about the schedule, commitments world information to identify contradictions to take appropriate action. If a new schedule cannot be generated without changing existing commitments, the component generate project (with information acquired from the component prepare project commitments) transfers information about the nature of the conflict to the component agent interaction management: commitment can only be acquired if a commitment with lower priority is cancelled, otherwise given the current priorities schedule, commitment is not possible. The component agent interaction management provides the information with which the Personal Assistant interacts with the Work Manager, to decide on new requests. Requests for cancellation of a previous commitment (with perhaps lower priority) may well be the consequence Requests for monitoring information A Personal Assistant also receives requests for monitoring information. These requests are forwarded by the component agent interaction management to the component cooperation management. Within the component cooperation management, the component monitor project is responsible for monitoring a project, providing the necessary information (through the output interface of the component cooperation management) to the component agent interaction management to communicate to the Work Manager. To monitor a project the component monitor project requests information on the current status of a schedule through the output interface of the component cooperation management to the component maintain world information. The component maintain world information, in turn, produces a request which is transferred to the component agent interaction management, which in turn transfers the request to the output interface of the Personal Assistant. This request is then forwarded to the Employee. 6.2 Interaction with the Employee The Personal Assistant requests information about current commitments schedules from the Employee. These requests are devised by the component maintain world information, often as a result of requests for information from the component monitor project within the component cooperation management. In addition, the component receives information from its Employee without having initiated interaction. An Employee may provide information on changes in his/her schedule without having been explicitly requested to do so. This information is forwarded directly to the component maintain world information, to the component cooperation management. Within the component cooperation management the component monitor project detects possible new conflicts. 7 The Employee Within the multi-agent system the Employee only interacts with his/her Personal Assistant, see Figure 4.2.Interaction with the Employee is modelled by the interface in the prototype system. The interface, see Figure 7, presents the contents of the agenda as received from the Personal Assistant. Furthermore, the interface allows for changes to be made to the agenda, which are 568

10 5.4.1 Generate Project Within the component generate project the component prepare project commitments receives the Work Manager s own goals to determine procedures that can be followed to achieve a given goal. This is performed using knowledge relating requests to procedures, for example of the following form: if then own_goal(appointment_request(service(credit_card))) selected_procedure(procedure(cp2)). To determine which activities are required to execute the procedure, knowledge is used that relates procedures to activities, knowledge that defines duration of, temporal relations between, activities; for example knowledge of the form: if then selected_procedure(procedure(cp2)) selected_activity(activity(a1), duration(5)) selected_activity(activity(a2), duration(3)) precedence(activity(a1), activity(a2)) Within the component generate project the component generate modify project recipe receives the selected activities, their duration temporal relations between them. It determines which Personal Assistant is capable of taking responsibility for a given activity (using agent information maintained in maintenance of agent information) proposes a schedule. This process is involves intensive interaction with the Personal Assistants may iterate a number of times, until the proposed schedule is accepted by all Personal Assistants Monitor Project Progress of the procedure is monitored within the component monitor project. If substantial deviations from the committed schedule are identified, this component determines which actions are to be undertaken. This process is described in more detail in Section 8. 6 Personal Assistant A Personal Assistant communicates with both the Work Manager the Employee. 6.1 Interaction with the Work Manager As described in Chapter 4, a Personal Assistant (PA) receives requests from a Work Manager for: 1. a commitment to a specific activity A before a certain deadline 2. (possibly with) additional information on the importance of the activity (priority P), the earliest starting time (E) the latest starting time (L). 3. cancellation of a commitment 4. monitoring information on a specific activity A. All Personal Assistants are modelled as the same refinement of the same part of the generic model of a co-operative agent presented in Chapter 3, namely a refinement with four components: the component own process control, agent interaction management, cooperation management, the component maintain world information Requests for commitment cancellation Requests for commitment are forwarded from the component agent interaction management to the component own process control. Within the component own process control it is decided whether or 567

11 5.1.2 Management of outgoing communication The component outgoing communication management prepares the following types of outgoing information: appointment proposals (to a Call Centre Agent) commitment requests (to a Personal Assistant) commitment confirmations (to a Personal Assistant) The information to be communicated is provided by the component cooperation management, transferred to agent interaction management through the information link cooperation info to AIM. Preparation of information includes, for example, labelling outgoing communication so that the agents that receive the information can refer to this information in their reply. Preparation of communication is performed using knowledge of the following type: if then prepared_appointment_info(i:info_element, S:SIGN) current_communication_identifier(i:cid) to_be_communicated_to(i:info_element, S:SIGN, CC:CALL_CENTRE_AGENT, I:CID) if then prepared_commitment_info(i:info_element, S:SIGN) current_communication_identifier(i:cid) to_be_communicated_to(i:info_element, S:SIGN, PA:PERSONAL_ASSISTANT, I:CID) Conclusions drawn using this knowledge are transferred to the output interface of the Work Manager through the information link info to be communicated, from the agent s output interface to the input interfaces of the agents to which the communication is directed (as discussed in Section 4). 5.2 Own Process Control The component own process control has two components: determine goals commitments maintenance of own characteristics. Within the component determine goals commitments requests communicated by the Call Centre Agents are analysed the decision whether or not to accept a request ( as a consequence adopt a goal to respond to the request as one of the Work Manager s own goals) is made. The agent s own characteristics are explicitly represented within the component maintenance of own characteristics. Examples of specific agent characteristic are: that a request for a certain type of client (e.g., for a known client) is to be given priority, or that requests for credit card services are processed with higher priority than student loan services. 5.3 Maintenance of Agent Information Within the component maintenance of agent information the Work Manager maintains information on the capabilities of the other agents. One example of information maintained by the Work Manager is the information a Work Manager has on the activities for which each Personal Assistant can be approached. 5.4 Co-operation Management The component cooperation management is composed as described in Section 3. Each of its components is discussed in more detail in this section. 566

12 determines a schedule for the activities in the procedure. The Work Manager asks Personal Assistants of those Employees selected to execute the schedule (this communication is managed by its component agent interaction management) whether or not they can commit to specific activities. If a proposed schedule is accepted by all relevant Personal Assistants, the Work Manager selects a set of possible appointments with the client communicates this set to the Call Centre. If not, the Work Manager needs to either adapt its schedule or choose another procedure, depending on the information communicated by the Personal Assistants. This process is discussed in more detail in this section. A Work Manager Agent is modelled as a refinement of the generic model of a co-operative agent presented in Section 3. At the top level of the agent only four components are used in this application: agent interaction management, own process control, maintenance of agent information, cooperation management. Each of these components is discussed in more detail below. 5.1 Agent Interaction Management The component agent interaction management is composed of two components: incoming communication management outgoing communication management. Communication can take place with either a Call Centre Agent or a Personal Assistant Management of incoming communication Within the component incoming communication management incoming communication is analysed communicated information identified. For example, the following types of information can be identified: a new request (from a Call Centre Agent) an answer (from a Personal Assistant) toone of the Work Manager s commitment requests for an activity in the context of an already accepted goal, a progress report on already scheduled activities (from a Personal Assistant); e.g., a reported delay. Depending on the type of information received, the implications for information to be provided to appropriate component(s) within the Work Manager are identified. For example, communicated information on a new request from a Call Centre Agent is needed by the Work Manager s component own process control, whereas the other two types of communicated information listed above are needed by by the component cooperation management. The identification preparation of communicated information is performed using knowledge of the following type: if then communicated_by(i:info_element, S:SIGN, PA:PERSONAL_ASSISTANT) new_cooperation_info(i:info_element, S:SIGN) if then communicated_by(i:info_element, S:SIGN, CC:CALL_CENTRE_AGENT) new_own_process_info(i:info_element, S:SIGN) Conclusions drawn using this knowledge are transferred to the components own process control (conclusions of the form new_own_process_info(i:info_element, S:SIGN)) cooperation management (conclusions of the form new_cooperation_info(i:info_element, S:SIGN)) by the two information links communicated info to OPC communicated info to CM, respectively. 565

13 requested information or a set of possible appointments. The Call Centre Agent communicates the appointment chosen by the client to the Work Manager. Interaction between Work Manager Personal Assistant A Work Manager can provide a Personal Assistant with a number of different types of information: a commitment request to perform a specific activity A before a certain deadline D. The request contains additional information such as the importance (priority) P of the activity, the earliest starting time E of the activity, the latest starting time L of the activity. a cancellation of the commitment to a specific activity A: the personal agent is no longer committed to activity A. a request for monitoring information regarding a specific activity A: the Work Manager would like to know whether the Personal Assistant can keep its commitment to activity A. A Personal Assistant can communicate two different types of information to a Work Manager a reply to a commitment request, monitoring information. Reply to a commitment request A reply from a Personal Assistant to a Work Manager contains one of the following: commitment: the Personal Assistant commits to activity A, with deadline D, priority P, earliest starting time E, latest starting time L. conditional commitment: the Personal Assistant commits to the request under the condition that the Work Manager relieves it of the commitment to activity A that has a lower priority P than activity A. refusal: the Personal Assistant cannot commit to activity A, with deadline D, priority P, earliest starting time E, latest starting time L. Monitoring information Monitoring information specifies whether a Personal Assistant expects its employee to be able to perform a specific activity A (within a given time slot). A Personal Assistant can report that a commitment A cannot be kept because: no start has been/ will be made at time L. the deadline D will not be met. the necessary information/material regarding A is not available. Interaction between Personal Assistant Employee On request, a Personal Assistant communicates the contents of the agenda to its Employee. An Employee informs its Personal Assistant of (self-imposed) changes to his/her agenda of changes to his/her own profile information. 5 Work Manager A Work Manager is free to decide whether or not to accept a request communicated by a Call Centre Agent. If, after interpretation of a request, a Work Manager decides to accept the request, this request is translated into a goal for the Work Manager to adopt.this part of the process of the Work Manager is modelled within the Work Manager s component own process control. To achieve the adopted goal, co-operation with Personal Assistants is required. Within the component cooperation management the Work Manager selects an appropriate plan (the procedure to which the Bank s description of the application domain referred) for this goal 564

14 Client Clients identify a need to consult their bank call their local bank with a request. If a client s request can not be answered directly, a set of possible appointments is proposed, from which the client can choose. The client s choice is the agreed appointment. Call Centre Agent Relatively simple requests are hled by the Call Centre Agent directly. Other, more complex, requests are forwarded to the Work Manager of an appropriate local bank by the Call Centre.. The Work Manager, in turn, informs the Call Centre Agent of a number of possible appointments for the client with a client advisor. The Call Centre Agent proposes these options to the client. Work Manager After interpretation of a request, the Work Manager selects an appropriate procedure for therequest creates a schedule for the activities in that procedure. The Work Manager communicates requests for commitment to the Personal Assistants of selected Employees. The Work Manager may have to adapt its schedule (or even choose another procedure) depending on the information received from the Personal Assistants. If the proposedschedule is accepted by all relevant Personal Assistants, the Work Manager determines when appointments can be made proposed this set of possible appointments. Section 5 contains a detailed description of the Work Manager. Personal Assistant Given a request for commitment a Personal Assistant checks the agenda profile of the Employee it represents (possibly) reschedules the Employee s agenda. The Personal Assistant informs the Work Manager of the degree to which it is possible to reschedule the Employee s agenda to meet the schedule the Work Manager has proposed. The Personal Assistant informs its Employee of the contents of his/her agenda of changes made in the agenda. Based on the information the Personal Assistant receives from the Employee, the Personal Assistant updates the Employee profile the agenda. If previous commitments made by the Personal Assistant cannot be met due to new appointments or modifications made by the Employee the Personal Assistant informs the Work Manager. Section 6 contains a detailed description of the Personal Assistant. Employee Employees check their agenda regularly, make changes to it according to their own needs preferences, execute the activities as scheduled in their agenda. Section 7 contains a more detailed description of the Employee Interaction between agents Figure 4.2 depicts the information exchange between the agents of the multi-agent system. The interaction between the different types of agents is described globally in this section. The internal composition of the agents are described in more detail in Sections 5, 6, 7. Interaction between client Call Centre Agent A client (or potential client) calls its local bank. The call is redirected to the Call Centre. The client communicates a request to the Call Centre Agent. The Call Centre Agent provides the client with either the requested information or a set of possible appointments from which the client can choose. The client informs the Call Centre Agent of his/her choice. Interaction between Call Centre Agent Work Manager The Call Centre Agent communicates a client-request for which an appointment must be made to the Work Manager of an appropriate local bank. The Work Manager responds with either the 563

15 2. The system has to maintain a profile for each employee that contains information on: a) the capabilities of the employee. b) the preferences of the employee (e.g., time periods during which the employee does or does not want to perform specific kinds of activities). c) the availability of the employee (e.g., holidays). 3. The system is only allowed to reschedule the agenda of an employee in a way that respects the profile of the employee. 4. The system has to be able to interact with the electronic agenda of every employee. Given the inherent distributed nature of the system (see Figure 4.1), the autonomy of the parties involved the importance of interaction between partiesan agent-oriented approach was chosen. 4.2 The agents their interaction Within the multi-agent system five types of agents play a role: Client: the clients are the initiators of requests Call Centre Agent: one agent of this type is modelled Work Manager: one agent of this type is modelled for every local bank Personal Assistant: for each employee one personal assistant is modelled Employee: for every employee an interface is modelled The prototype multi-agent system consists of one Client, one Call Centre Agent, one Work Manager, two Personal Assistants two Employees, see Figure 6. pa A1 to wm wm to call center Work Manager wm to pa A1 P ersonal Assistant A1 pa A1 to empl A1 empl A1 to pa A1 Employee A1 Client client to call center Call Center Agent call center to wm wm to pa An empl An to pa An call center to client clock P ersonal Assistant An pa An to empl An Employee An pa An to wm Figure 6 A multi-agent system for a local bank A global clock is modelled to ensure that the schedules of the Personal Assistants are synchronised with the schedules of the Work Manager. Each of the tasks described in Section 4.1 is delegated to one or more of the agents in Section Figure 4.2 depicts the information exchange between the agents of the multi-agent system. The interaction between the different types of agents is described globally in Section The internal composition of the Work Manager, the Personal Assistants, the Employees are described in more detail in sections 5, 6, The tasks of the agents In this section the tasks of each type of agent are sketched. The Work Manager, the Personal Assistants, the Employees are described in more detail in Sections 5, 6,

16 Determine Consequences (DC) interprets AV's monitoring results. The component DC issues requests to find new recipes or to adapt existing recipes, to the component project generation of CM issues corresponding communication to the participants. DC also determines when a goal G should be withdrawn (for example, because the goal is unattainable, the goal has been reached, or because the motivation for the goal no longer exists) prepares issues communication to that effect to each participant. 4 The multi-agent system to support a call centre This section explains the choice for developing an agent oriented model for the problem. Furthermore, the conceptual model of the multi-agent system is described. 4.1 The multi-agent perspective The problem description in Section 2 clearly defines the problem as a distributed problem: there is one call centre for several local banks (see Figure 5). Client Local Bank Work Manager Agent Call Center Agent Client Local Bank Work Manager Agent Figure 5 One call centre for several local banks To design systems for the call centre the local banks the tasks to be performed have been identified. As discussed in Section 2, the main task of the system is to provide a set of possible client appointments in response to a complex request: 1. a request must be interpreted by the work manager to see whether or not its bank can hle the request. 2. if the request can be hled, then an appropriate procedure must be selected. 3. a schedule must be devised for the activities in the procedure such that: a) the schedule can be met by the co-operative work of the employees of the bank. b) time is reserved within the agendas of the employees involved for the activities in the schedule. 4. a number of possible client appointments are proposed. 5. agreed client appointments are placed in the agendas of the relevant employees. To perform the above tasks appropriately, the system has to satisfy the following: 1. The system has to cope with changes made by employees. An employee can change his/her agenda, s/he can: a) refuse to perform a specific activity. b) refuse to perform it within a specific period of time. c) reschedule his/her agenda. d) delay some of the activities 561

17 Generate Project (GP) Given the goal G, motivation M, priority p, deadline T, all possible sets A of activities with which goal G can be reached, an agent's own capabilities, the component generate project has two main processes: to prepare project commitments, to generate modify project recipes. Links are defined to regulate the interaction between generate project's components its environment, see Figure 3. The component Prepare Project Commitments (PPC) determines a preferred set A of activities with which goal G can be reached. Using domain-knowledge the dependencies between the activities in A are determined. Given this dependency-graph prepare project commitments determines which agents can are willing to perform activities to help reach goal G (e.g., using the employee profiles). PPC provides the dependency-graph for A, the information (G, M, p, T), the relevant capabilities of the willing participants (including the agent's own relevant capabilities) the corresponding names of the agents. The component Generate Modify project Recipe (GMR) designs a recipe R that conforms to the interdependencies between the activities in A (thus leading to G's fulfilment). The recipe R is interactively designed by iteratively generating sending proposed recipe elements to agents interested in participation. A recipe element consists of an activity of A, a willing participant capable of performing that activity, a priority p a deadline T for that activity. The willing participants accept, adapt or reject the proposed recipe elements. GMR adjusts the partial recipe depending on the replies from participating agents. A recipe may be found that is acceptable to all participants that will reach goal G before its deadline. The time required for communication (depending on the situation) is assumed to be known. In addition, communication is assumed to be error free. The resulting recipe is communicated to all participants. Monitor Project (MP) The component monitor project is responsible for the detection of the need for alterations to the project or the need to stop the project. MP monitors the progress of the project. In order to perform its task MP has two components: assess viability determine consequences. These components the links for interaction within MP are depicted in Figure 4. Assess Viability (AV) monitors the viability validity of the recipe. To monitor the process AV uses information on the progress of the activities of the participants, information on the current world state. AV can also actively formulate requests for information. Monitor Project - task control structure assessment info to output Assess Viability Determine Consequences project info assessment info to DC info on project changes Figure 4 Monitor Project 560

18 3.2 Cooperation Management A global description of the co-operation model is presented in this section, the model is described in more detail in (Brazier, Jonker, Treur, 1997). The component cooperation management is a composed component responsible for all processes concerning projects, project commitments co-operation. It consists of two components; one for the generation of projects one for the monitoring of existing projects. The interaction between the components of cooperation management cooperation management's environment, between the components of cooperation management is defined by the links depicted in Figure 2. Cooperation Management - task control structure monitoring_info incoming_project_info Generate Project Monitor Project required_project info_on_other_agents own_generated_project required_info_on_other_agents commit ments_to_output required_monitoring_info monitoring_info_to_output Figure 2 Co-operation management cooperation management needs the following types of information: goal, deadline, necessary activities: to create a new project capabilities of other agents: to find participants for a project commitments of other agents: to build a joint recipe observation information: to monitor existing projects communicated project information: to monitor existing projects cooperation management provides the following types of information: recipe elements relevant for possible participants joint recipe relevant for all participants monitoring information relevant for all participants Generate Project - task control structure needed info on other agents recipe to be repaired recipe to be prepared info on other agents to PPC Prepare Project Commitments info on participants prepared project Generate Modifye Project Recipe info for agents Figure 3 Generate Project 559

19 3.1 A Generic Agent Model This section describes a generic agent model in which generic agent tasks are modelled. This model abstracts from the specific domain of application can be (re)used for a large variety of agents. Instead of designing each every new agent individually from scratch, a generic agent model is used to structure the design process: the acquisition of a specific agent model is based on the generic structures in the model. The model is based on the abilities associated with the notion of weak agency (Wooldridge Jennings, 1995). The characteristics of this notion of agency provide a means to reflect on the tasks an agent needs to be able to perform. Pro-activeness autonomy are related to an agent's ability to reason about its own processes, goals plans to control these processes (own process control (OPC)). Reactivity social ability are related to the ability to be able to communicate with other agents (agent interaction management (AIM)) to interact with the external world (world interaction management (WIM)). The ability to communicate with other agents to interact with the external world often relies on the information an agent has of the world (maintenance of world information (MWI)) other agents (maintenance of agent information (MAI)). The generic agent model also includes an empty generic component to model the agent specific task (AST). The ability to co-operate with other agents relies on the ability to plan schedule activities (own process control cooperation management (CM)) the ability to make commitments between agents (cooperation management). The task cooperation management is the topic of Section 3.2. The tasks related to the generic abilities agent specific tasks are modelled by components within the agent model depicted in Figure 1. In addition to components, the model includes information links that specify which information is exchanged between components; these information links are named. More information on the information links in Figure 1 can be found in (Brazier, Jonker, Treur, 1997). agent task control structure info _to_be_communicated self_info_request coo peration_info_ to_ OPC OPC MH AST communicated_info_to_opc self_info_for_coop eration communicated_ info _to_cm CM other_agents_info_ for_coop eration communication_ to_be_ performed incoming _ observ ed_ wor ld_ inf o AIM incoming _ communicated_info WIM communicated_ agent_info observed_world_info_to_cm communicated_world_info observed_world_info MAI other_agents_info_request world_info_ to_ CM MWI required_world_info required_observ ations world_interaction_to_be_performed Figure 1 A Generic Agent Model 558