the instantiation constraints which connect variables of ai and of aj concerning the property p are contained in I. 

## Definition 5.7 (Hypothesis)

Let's a conjecture χ=(A, <, I, C). A hypothesis formulate by χ is defined as a precondition p of an action aj ∈ A such as for all actions ai∈ A, the causal link aj p ai ⎯⎯→ ∉ C. 

## 5.3. **Agents Role And Tasks** 5.3.1. Manager Agent

The manager agent makes sure that the description of an imported service is substantial with regard to the sub-ontology by controlling, in particular, its operations, its inputs and its outputs which have to be concepts of the corresponding sub-ontology. It stores all the OWL-S descriptions of services and the localizations of its suppliers. At the composition time, the manager agent corresponds to a Web service. It is initialized with the semantic description of the service and with a set of data allowing it reasoning. For example, an agent representing a service of booking of railroad transport has the list of the existing courses. These data form the knowledge base of the manager agent. From the semantic description, a manager agent is going to create its planning domain which includes, under the form of methods and operators extracted from the processes of the OWL-S description, the practicable actions by the agent, i.e., its base of competences. 

## 5.3.2. Request Re-Constructor Agent

The request re-constructor agent has for main task to reconstruct the "user request" from the descriptions recorded in the global ontology of the Web services. This one supports, at the same time, the atomic and composite services. The result of this task is an OWL-S file. 

## 5.3.3. General Manager Agent

This agent has for main role to verify if the request represents the description of a composite service. In this case, the general manager agent invokes the composer agent, that invokes the agents concerned by the request. On the other hand, if the request user concerns an atomic service, the general manager agent invokes directly the concerned manager agent because it has a global view of the system. 

## 5.3.4. Composer Agent

The composer agent has for role to coordinate and to assembly the manager agents to execute the required operations. It also initializes the composition process by sending to the manager agents the goal to be realized under the form of a first conjecture which represents the initial plan. 

## 5.4. **Main Tasks Involved In The Composition Process**

The first task is user request construction. To make that, the user retrieves a special interface. 

After the user has finished its request construction, a request reconstruction step is made by the request constructor agent. To reconstruct a request, the request constructor agent retrieves OWL-S available services descriptions that are stored in the global BPs Ontology and which supports both atomic and composite processes. Once the user request is semantically described, the general manager agent must be able to determine if the user request can be executed by one atomic service or by composing multiple 