The name is absent

(2) the blackboard, a shared data structure through which the knowledge sources communicate
with each other by means of the creation and modification of solution elements; (3) the
communication mechanisms, which establish the interface between the nodes, and the
interface between a given node and the external or internal media; and (4) a control
mechanism, which determines the order in which the knowledge sources will operate on the
blackboard.

The main characteristics exhibited by the blackboard architecture and desired in the
implementation of behaviours production systems include the following: (1) a high capacity of
coordination and integration of many activities in real time, (2) great flexibility in the
incorporation of new functionality, (3) the handling of the action selection as knowledge
selection in problem solving, and (4) the opportunism in problem solving. These characteristics
support the evolutionary and bottom-up construction approach of our BPS discussed in the
next sections.

3.4. Behavioural Columns Architecture: An Evolutionary Bottom-Up Approach

“Everything should be made as simple as possible, but not simpler”

—Albert Einstein

In this section we will present the basic components of our BPS, which we refer to as
Behavioural Columns Architecture (BeCA) (Gonzalez, 2000): the set of internal behaviours,
the blackboards and their levels, the interface/communication mechanisms, the emergent
behavioural columns, and the blackboard-nodes.

Internal behaviours are information processing mechanisms that operate within the
BPS, whose function involves the creation, combination, and modification at different
blackboard levels¹⁶. An internal behaviour in BeCA is equivalent to a knowledge source in the
blackboard node architecture or a hidden layer in an artificial neural network. Internal
behaviours can also be seen as agents embedded within node agents, and composed of
elementary agents. Internal behaviours are constituted by elementary behaviours, which can
be seen as the rules that are packed in a knowledge source in the blackboard architecture, or
an artificial neuron in a neural layer. An elementary behaviour has three elements: a list of
parameters, a condition component, and an action component. The list of parameters specifies
the condition elements, the action elements, and the coupling strengths related with the
elementary behaviour. The condition of an elementary behaviour describes the configuration
of signals that is necessary on the blackboard, so that the elementary behaviour contributes to
the solution processes of the problem. The way in which an elementary behaviour contributes
to the solution of the problem is specified in its action, which can consist in the creation or
modification of solution elements in certain blackboard levels. A coupling strength is
represented by a vector Fa = (Fa_i1, Fa_i2,..., Fa_in) of n real components, where each of these
components represents the efficiency with which an elementary behaviour can satisfy a

¹⁶The names of internal behaviours in BeCA will be typed with italics throughout the text.

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