@InProceedings{PezzuloGiangulielmo2004,
author = {Giovanni Pezzulo and
Gianguglielmo Calvi},
title = {A Pandemonium Can Have Goals},
booktitle = {Proceedings of the Sixth Annual International Conference on Cognitive Modelling (ICCM2004)},
year = {2004},
pages = {237-242}
}
AKIRA[p237]
AKIRA is an open source multi agent system for cognitive and socio-cognitive modeling and simulations.
Because of its agent-based system, hybridism of connectionist and symbolic components,
common pool of resources, and it functioning as a homeostatic system. AKIRA is extremely
powerful in what it can represent.
AKIRA has a MACRO language and many templates that allow for the building of agents of
varying complexity. The entire system is written in C++.
Pandemonium metaphor (Jackson, 1987)[p237-238]
The pandemonium metaphor has several components: The Pandemonium (kernal), Daemons
(micro-agents), Coalitions (Daemon sets), Blackboard (XML stream), and Energy Pool
(abstraction for computational resources)
The Pandemonium is the main process that identifies which Daemons to load and which
monitors the Blackboard and the individual agents.
Daemons are the minimal elements to this system. They include their priority (set by
the programer), their current activation level (that is how relevant they are), their tap
power (their access to the resources), their symbolic operation (the functional body), a
labeled link list (this points other Daemons and is the source of spreading activation).
They are also hybrid in that they have a symbolic side, they can execute their
function if all conditions are met or "shout" to let other Daemons know their status via
the Blackboard, and a connectionist side, they can tap energy from the Energy Pool, spread
it to other Daemons, release it back to the Energy Pool, and join other Daemons in
Coalitions
Coalitions are the communities of cooperating Daemons that are created to solve
problems that are too complex for any one Daemon to handle. They come in two flavours
Bands and Hordes. Bands come about after a Daemon shouts for help with a non-atomic
problem and other Daemons answer and join, thus it is bottom-up. Hordes arise from
specialized Daemons called Archons which have a structure as their symbolic
operation that looks for specific class of Daemons to fill the roles, thus it is
top-down.
The Blackboard is a shared data structure where Daemons read and write messages.
Messages can be addressed to specific Daemons, a class of Daemons, or everything.
The Energy Pool is a global variable with a finite quantity. Daemons can
request some of the energy and thus they all exist in a concurrent environment with
limited resources.
Agent-based cognitive and socio-cognitive modeling and simulation[p238-239]
One of the main requirements of AKIRA was the ability for higher-order cognitive modeling, especially to exploit the BDI-like constructs. AKIRA is also has goal-directness, being able to exploit both top-down organization and parallel and concurrent computation.
Hybridism of connectionist and symbolic components[p239]
Daemons have both a symbolic component and a connectionist component.
The symbolic component is the set of operations a Daemon can perform via its symbolic
operations. These operations can be simple or complex but because of the concurrent
nature more complex operations are more commonly done by several Daemons. This side
of AKIRA allows the use of top-down drives and structures.
The connectionist component is the activation level of the Daemon itself as well
as the energy exchange between Daemons. This side of AKIRA allows the use of
the emergent and distributed properties of cognitive and soci-cognitive phenomena.
Because of its hybrid nature Daemons also allow symbolic and connectionist learning.
Homeostatic systems[p239]
Because of the common pool of Energy there are two metaphors that are used to understand
the Daemon dynamic. The Energetic Metaphor (Kokinov, 1994) and the Physical Work Metaphor.
The Energetic Metaphor (Kokinov, 1994) states that the greater the activation the
greater the computational power that is being used. Thus Daemons with more energy have
priority for their symbolic operations and their energetic exchanges. This allows
phenomena such as context and priming effects to be modeled and explored with AKIRA.
The Physical Work Metaphor states that as work is done energy is expended. Ergo
symbolic operations have an energy cost that must be paid by the performing Daemon. Thus
the system is conservative.
This common pool also allows urgency and pressures to be introduced to the system. Because
each operation has an energy cost more urgent operations will have lower energy costs then
less urgent operations. So urgent operations are much more likely to be preformed in any
given situation then less urgent operations. The collection of Daemons, by their very
presence, puts pressure on the other Daemons as they compete for energy.