Page 279 - Socially Intelligent Agents Creating Relationships with Computers and Robots

262 Socially Intelligent Agents

bidder is committed to subsequently pay for the acquired good. Obligations
and prohibitions are captured by means of normative rules.
Based on the institution components introduced above, in [8] we offer a
formal specification of electronic institutions that founds the computational
model presented in Section 4.
4. Agent-mediated Institutions

The workings of an electronic institution can be fully realised by means of
the articulation of two types of agents: institutional agents and interagents.
Institutional agents are those to which the institution delegates its services,
whereas interagents are a special type of facilitators that mediate all the in-
teractions of external agents within an electronic institution and enforce insti-
tutional rules. Our agent-mediated computational model (thoroughly detailed
in [8].) has proven its usefulness in the development of FM96.5, the compu-
tational counterpart of the fish market [10], which served as the basis for the
subsequent development of FM, an agent-mediated test-bed for auction-based
markets[9].

4.1 Institutional Agents
An institution delegates part of its tasks to agents adopting institutional roles
(in the fish market the auctioneer is responsible for auctioning goods, the sell-
ers’ admitter for registering goods, and the accountant for the accounts’ book-
keeping). We refer to this type of agents as institutional agents. An institutional
agent can possibly adopt multiple institutional roles. In order to fully specify
an institutional role we must specify its life-cycle within an institution in terms
of its responsibilities along with the policy of responsibilities’ management.
More concretely, we specify an institutional role’s life-cycle as a regular ex-
pression built by combining the following operations: x.y (x followed by y),
∗
x (x occurs 0 or more times), x||y (x and y interleaved), x|y (x or y occurs),
+
x (x occurs 1 or more times), [x] (x is optional); where x and y stand for scene
(activity) names. Table 32.1 contains the specification of the buyer admitter,
auctioneer and seller accountant roles in FM96.5, the computational coun-
terpart of the fish market. For instance, an institutional agent playing the
buyer admitter role must firstly enter at the registry scene with the boss of
the market. Next, it is expected to meet other institutional agents (auctioneer,
buyers’ accountant, sellers’ admitter and sellers’ accountant) at the opening
scene. Afterwards it can start processing buyers’ requests for admission.
Institutional agents might be required to comply with several responsibilities
at the same time. In such a case, an institutional agent must know how to priori-
tise (schedule) simultaneous responsibilities. For this purpose, responsibilities
are ranked according to their relevance. As an example, the responsibilities