Robert Axelrod (1976) inaugurated the use of cognitive maps (CMs) for formally modeling decision making processes associated with political and social systems. CMs are directed graphs capable of modeling interrelationships or causalities existing amongst concepts (nodes). Concept variables and causal relations constitute the two fundamental elements that CMs employ for graphically describing systems. Concept variables are represented by nodes, such as C1, C2, C3, and C4 in Figure 1, a basic CM having four concept variables describing the impact of "Electromagnetic interference in the reading of an ultrasonic sensor".
Causal variables always depict concept variables at the origin of arrows; effect variables, on the other hand, represent concept variables at the terminal points of arrows. For example, in looking at C1 and C2 in the figure, C1 is said to impact C2 because C1 is the causal variable, whereas C2 is the effect variable.
Fuzzy cognitive maps
In this article we recall the notion of Fuzzy Cognitive Maps (FCMs), which was introduced by Bart Kosko[1] in the year 1986. FCMs have a major role to play mainly when the data concerned is an unsupervised one. Further this method is most simple and an effective one as it can analyse the data by directed graphs and connection matrices.
DEFINITION: An FCM is a directed graph with concepts like policies, events etc. as nodes and causalities as edges. It represents causal relationship between concepts. [2]
In other words, a Fuzzy cognitive map is a cognitive map where the relations between the elements (e.g. concepts) of a "mental landscape" can be used to compute the "strength of impact" of these elements. and one of its applications is to mapping mobile autonomous robots path.
According to Bart Kosko "Fuzzy cognitive maps are fuzzy-graph structures for representing casual reasoning. Their fuzziness allows hazy degrees of casuality between hazy casual objects(concepts). Their graph structure allows systematic casual propagation, in particular forward and backward chaining, and it allows knowledge bases to be grown by connecting different FCMs. FCMs are especially applicable to soft knowledge domains. Causality is represented as a fuzzy relation on causal concepts."[1]
[1] Kosko, B. Fuzzy cognitive maps. International Journal Man-Machine Studies (1986) no. 24, pp. 65-75.
[2] Vasantha, W. B. Fuzzy cognitive maps Neutrosophic cognitive maps. 2003
Author
David Alejandro Trejo Pizzo. IEEE Member and researcher @ AIGROUP, working in the FIC Project. Student @ Universidad de Palermo.