Search all paths and the shortest path for a chart - Prolog

Question

I have a problem in my code with a turbo prolog that searches all paths and the shortest path in a graph between two nodes. The problem I have is to check if the node is in the list or not (exactly in the member section)

1 ---- b ---- 3 --- | --- --- | ----- a |5 d --- | ----- --- | --- 2 --- | --- 4 -- c -- for example we have for b--->c ([b,c],5) , ([b,a,c],3) and ([b,d,c],7) : possible paths. ([b,a,c],3) : the shortest path. 

and this is my code:

 DOMAINS list=Symbol * PREDICATES distance(Symbol, Symbol) path1(Symbol, Symbol, list, integer) path(Symbol, Symbol,list, list, integer) distance(Symbol, list, integer) member(Symbol, list) shortest(Symbol, Symbol, list, integer) CLAUSES distance(a, b, 1). distance(a, c, 2). distance(b, d, 3). distance(c, d, 4). distance(b, c, 5). distance(b, a, 1). distance(c, a, 2). distance(d, b, 3). distance(d, c, 4). distance(c, b, 5). member(X, [X|T]). member(X, [Y|T]) :- member(X, T). absent(X, L) :- member(X, L), !, fail. absent(_, _). /* find all paths */ path1(X, Y, L, C) :- path(X, Y, L, I, C). path(X, X, [X], I, C) :- absent(X, I). path(X, Y, [X|R], I, C) :- distance(X, Z, A), absent(Z, I), path(Z, Y, R, [X|I], C1), C = C1 + A . /* to find the shortest path */ shortest(X, Y, L, C) :- path(X, Y, L, C), path(X, Y, L1, C1), C < C1. 

Answer 1

This shows the shortest path and weight:

 edge(a,b,6). edge(a,c,1). edge(b,d,5). edge(c,e,4). edge(c,f,1). edge(d,h,3). edge(e,h,7). edge(f,g,2). edge(g,h,1). path(X,Y,M,[Y]) :- edge(X,Y,M). path(X,Y,P,[Z|T]) :- edge(X,Z,M),path(Z,Y,N,T), P is M+N. pravilo(X,Y,Z) :- assert(min(100)),assert(minpath([])),!, path(X,Y,K,PATH1), (min(Z),K<Z, retract(min(Z));assert(min(K))), minpath(Q),retract(minpath(Q)), assert(minpath([X|PATH1])), fail. ?- pravilo(a,h,X); write("Minimal Path:"), minpath(PATH), write(PATH), nl, write("Path weight:"), min(Z), write(Z). 

Answer 2

Not knowing what the problem is, I can at least suggest that perhaps shortest () and path () should take the maximum length parameter that closes the search.

In addition, shortest () does not find the shortest path. He finds for each possible pair of paths the shortest of each pair.