Interacting with the Problem Structure Manager

The interaction between the interface manager and the KSM model generating the answers is supported by a predicate-based communication protocol. These predicates are used to configure the content of questions and answers. The structure of a question interpreted by the Dialog Manager always includes the object about which the query is formulated, some condition or action related to the context of the object, and the interaction modes associated to the question. Once the Dialog Manager delivers a question to the Problem Solving Model, this acknowledges the message with an estimation of the time required to generate the corresponding answer. All the answers provided by the Problem Solving Model have the same structure. It distinguishes three parts:

Description:

A high level formulation of the information required about the object of the question.

Elaboration:

A description of the aspects that give support to the answer provided in the description argument. This part could make a recursive use of the answer structure if the information of the object is supported by information related to the components of the object. For instance, the state of a line is obtained from the state of its vehicles so the class of situation observed in a line may be provided in the description argument whereas the elaboration argument may include the state of the problematic vehicles in the line.

Explanation:

It contains textual information that justifies the conclusions offered in the previous arguments.

Three main classes of query-response patterns can be distinguished:

• A current_situation structure provides the answer to a query of the type what_is_happening(object, mode), where object in the given application is usually something like a specific line or vehicle. The mode argument is a list of options to control the reasoning process (e.g. level of detail).
• A structure of the type foreseable_situation relates to a
  what_may_happen(object, conditions, actions, mode) query. The conditions and actions parameters can be used to formulate conditional queries (e.g. ``if the average speed is higher than N'', ``if the vehicle X is removed'').
• Accordingly, a proposed_action structure corresponds to a query of the type what_to_do(object, conditions, mode).

The predicates used in the definition of the Description and Elaboration arguments of any answer can refer to (i) state information of vehicles, lines, certain directions of the lines or the whole public transport network; or (ii) simple or composed control actions.