Artificial Intelligence and Soft Computing: Behavioral ... - Arteimi.info

Else Flag:= true;
End;
Until no-of firing = no-of-transition;
Par End;
End.
The above algorithm has been applied to the Petri net of fig. 22.17 and its
trace is presented in table 22.1.
Table 22.1: Trace of the algorithm on example net of fig. 22.17
Time slot Tran
.
First tr1
cycle tr2
Second tr1
cycle tr2
Third
cycle
tr1
tr2
Set of c-b Set of u-b Flag=0, if c-b⊄ u-b
=1, if c-b= u-i≠{φ}
{r/x,d/y,a/z} {{φ}}
0
{n/x,a/y} {{φ}}
0
{r/x,n/y,a/z} {{r/x,d/y,a/z}} 0
{d/x,a/y} {{n/x, a/y}} 0
{r/x,d/y,a/z}/ {{r/x,d/y,a/z}, 1
{r/x,n/y,a/z} {r/x,n/y,a/z}}
{n/x,a/y}/ {{n/x, a/y}, 1
{d/x,a/y} {d/x, a/y}}
22.5.5 The Modular Architecture of the Overall System
It is evident from the discussion in section 22.5.3 that most of the possible
forms of parallelism of logic programs can be represented by Petri nets.
Section 22.5.4 described a scheme for concurrent resolution of multiple
clauses in a logic program. This section includes a mapping from Petri nets to
logic circuits for efficient realization of the algorithm presented in the last
section on a high speed inference engine.
Before executing the program, a compiler, specially constructed for this
purpose, is employed to parse the given program for syntax analysis. On
successful parsing, the variables used in the programs are mapped onto a
specialized hardwired unit, called Transition History File (THF) register.
The compiler also assigns the value of the variables, hereafter called tokens, at
specialized hardwired units, called Place Token Variable Value Mapper
(PTVVM). The sign of the arc function variables is also assigned to the
PTVVM by the compiler.