Information Technology Reference
In-Depth Information
All environments, even the simplest ones, introduce complex dynamics in the
model (as shown in [4]). The most important environment-related aspect of this
model to be aware of is that the food input is relatively constant each round and
sublinear to the number of harvesters. As a rule, the gain for each additional
harvester is marginal when the number of harvesters is above 20.
4.2 Agents
Human Agents.
Human agents are entities populating the world. They are
described by the following variables:
hp
[0
,max hp
]: hit points or physical condition. This value decreases when
the agent is attacked. If this value reaches 0, the agent dies.
max hp
is set to 10
in the simulation.
energy
∈
[0
,max energy
]: remaining energy. If this value reaches 0, the agent
dies of starvation and decreases by 1 every round. An agent with less than
max energy/
2 units of food is
hungry
(it cannot reproduce), otherwise it is
well fed
.
max energy
is set to 400. Modifying
max energy
impacts the sensi-
bility of the population growth to external conditions: the lower this value is,
the more the population fluctuates between periods of richness and extensive
storage followed by overgrowth and starvation.
bag
∈
: amount of carried food. It is filled when agents perform the
harvest
action and its content can be
stored
in the village.
culture
∈
N
[0
,
1]
n
: a vector representing the cultural orientation of the agent
(e.g. values and practices [7]), inspired by the Sugarscape cultural model [5].
Values of this vector are abstract, but can be used to compare inter-individual
cultural similarity using Euclidean distance. This vector changes randomly with
time (cultural innovation, change in opinion and divergence) and is be shared
amongst individuals via the
harmonize culture
action or inter-individual com-
munication. Thus, inter-individual cultural distance evolves with time: it in-
creases with the number of inhabitants and decreases with cultural sharing. We
empirically set
n
to 50.
n
impacts on the variability of individual culture, but
this impact is relatively low when
n>
20.
culture
defines the
loyalty
∈
[0
,
1]
towards the leader. The farther the distance of the agent's culture and the cul-
ture
culture
v
of the village, the lower this agent is loyal. Formally,
loyalty
=
1
∈
is an arbitrary constant to adjust
the impact of cultural distance over loyalty. In our case
α
is 0
.
05.
job
−
α.distance
(
culture,culture
v
)where
α
∈
R
: the activity to be performed dur-
ing the “perform job” phase. A
harvesting
human moves to the closest food
patch, collects it and drops its bag in the village. A
protecting
human is a mem-
ber of the police. It is inactive during the “perform job” phase but increases
the probability of the villagers to be under control in the “meet other humans”
phase.
Cultural Harmonizers (CHs)
unify the culture of the village in performing
the
harmonize
action. This action sets the
culture
vector of 10 human agents
to the village culture
culture
v
.
∈{
harvest, protect, harmonize culture
}
