Transition Networks

Abstract

Transition networks (TN) are made up of a set of finite automata and represented within a graph system. The edges indicate transitions and the nodes the states of the single automata. Each automaton stands for a non-terminal symbol and is represented by its own network. The edges of each single network are denoted by nonterminal or terminal symbols and thus refer to other networks or final states. If the structure of a transition network also allows for recursive processes, for example, in the substitution of an object by another object belonging to a higher hierarchy level (e.g. a verb becomes a verbal phrase), this type of network is known as a recursive transition network. A path traversing the transition network starts at a first network and, beginning at the starting node, passes along the single edges. When it encounters a non-terminal symbol, the system branches like a sub-program to the corresponding network until finally all non-terminal symbols have been substituted. If different substitution possibilities are available, several paths between starting state and final state of the respective finite automaton exist. Figure 5.1 shows a transition network for expressions in natural language which may generate expressions such as “conductor likes singer,” “a singer hates the conductor,” “a singer likes a conductor hates the singer”.