environment and especially to improve, using seman-
tics, the existing processes in the field of multi-agent
located in a 3D environment. This paper discusses
an ongoing research on the design of a multi-agent
system based on a semantic indexing of IFC objects.
This indexing process allows to build dynamically an
informed environment (composed of 3D objects se-
mantically indexed) and intelligent agents that can re-
act to the environment according to a context of use.
The new section presents the existing works on us-
ing semantics in Multi-Agents Systems. Section 3
overviews the proposed the principle of the envi-
ronment representation and the architecture of the
semantic-based environment generation tool. Finally,
Section 4 concludes this work and draws several per-
spectives.
2 BACKGROUND
This paper is located in the domain of the simulation
of buildings flows with situated multi-agent systems.
A multi-agent system (MAS) is a system composed of
multiple interacting intelligent software agents (Fer-
ber, 1995). Multi-agent systems can be used to solve
problems that are difficult or impossible for an in-
dividual agent or a monolithic system to solve. A
multi-agent system is situated when the agents are
immersed inside an environment. In the domain of
buildings simulation, an agent is assumed to be a
pedestrian, or any object that owns an autonomous
decision-making process. The environment is then
everything that is not an agent in the buildings.
Three different points of view may be adopted
to study the notion of environment in situated MAS
(Weyns et al., 2007): (i) the part of the system
which is outside the community of the agents; (ii) the
medium for coordination among these agents; or
(iii) the running infrastructure or platform. Weyns
et al. distinguish between the physical environment
and the communication environment (Weyns et al.,
2006). The physical environment provides the laws,
rules, constraints and policies that govern and support
the physical existence of agents and the other entities.
In the rest of this paper, only this aspect of the envi-
ronment is taken.
Several problems may be solved to properly im-
plement an environment: its topological and geomet-
rical description, its dynamics, and the meanings of
each object and zones in the environment. The two
first points are addressed by the JaSIM environment
model (Galland et al., 2009). The last point is ad-
dressed by both the integration of semantics in the en-
vironment and modification of the agent’s algorithms
that uses them. Most of the approaches found in the
literature are based on the tagging process of the en-
vironment.
• Tagging is Often used as a Kind of Semantic.
The concept of tagging consists in placing some
tags in the environment to inform agents on var-
ious subjects. Basically, tags are considered as
objects placed in the scene, but they do not have
a physical presence. They are invisible for the
viewer of the scene and are only being seen by the
agents. Our proposal includes to describe through
tags the usage of some places, i.e. where an agent
can sit, pass through, etc. Lugrin and Cavazza
(Lugrin and Cavazza, 2007) places various tags
on a single object. These tags are linked between
and can also represent information. For example,
a glass will be represented by a geometry and two
tags. The geometry will deserve its representa-
tion and also dimensions in the simulated world.
The first tag is a “containing” tag that will notify
agents that the object on which this tag is applied
can contain some things. The second tag is an
“opening” tag that will represent the fact that the
object is opened, and then the inside of this object
is accessible. These two tags are linked together
to represent the fact that if an agent interact with
the “opening” tag, that will affect the state of the
“containing” one. Finally, a last link is made be-
tween the “opening” tag and the environment to
represent the fact that the opening is accessible di-
rectly from the environment space.
In this proposal, the evolution of an object is done
by modifying the tags and links of this object. For
example, if the glass is clogged, the link between
the opening tag and the environment is deleted
and this tag is no more accessible from the en-
vironment.
Yersin et al. (Yersin et al., 2005) propose to imple-
ment a navigation graph with the help of tagging.
This approach consists in covering the maximum
amount of navigable areas with a minimum num-
ber of discs covering these areas and not overlap-
ping any obstacle. These discs overlap themselves
and form a navigation — center to center — graph
in which agents are sure to do not collide with
any obstacle. Moreover, these discs have labels
to define the name of the zone in which they are
located. These labels are very useful to select a
target without knowing its position in the environ-
ment.
• Using Roles in Addition of Tagging. In a sim-
ilar way, De Paiva et al. (De Paiva et al., 2005)
propose to put labels on areas in order to asso-
ciate a name with a position. But in opposite to
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