further to all-bidirectional-search-paths

Stewart Wallace <stewart.wallace <at> dictionaryofsydney.org> writes:

Further experimenting suggests that the normal behaviour for this function is to
only return the shortest path - it will return more than one only if there are
several the same length. If there is some way to make it return all paths up to
max-depth n, I would be very interested to know.

I have attempted to use the Prolog equivalent - bidirectional-search-paths - as
an alternative as the doco on it suggested more explicitly that it iterates
through multiple returned paths but I've struck another problem here because it
just seems to return nil paths.  I've set it up as follows:

(setf mn1 (upi !mp1:MajorNode_1))
(setf mn2 (upi !mp1:MajorNode_2))
(?- (bidirectional-search-paths (?? mn1) (?? mn2) (?? nextN) 11))

.. nextN is the generator previously defined in my previous post - (setf nextN
(defsna-generator nextNode () (:undirected :p (!mp1:hasNextNode))))
 
The exact equivalent lisp version - (all-bidirectional-search-paths
!mp1:MajorNode_1 !mp1:MajorNode_2 nextN 11) - returns at least a path but the
Prolog one just returns nil - can't see what I'm doing wrong.

I've also noticed that AllegroCL doesn't seem to want to recognise some of the
other Prolog functions mentioned in the doco like:

(?- (nodal-neighbors (?? mn1) (?? nextN)))

.. this just gives and unrecognised-function error.  Are all the documented
Prolog SNA functions (those in
/support/documentation/current/reference-guide.html#header3-68 under the
subheading 'Prolog and Social Network  analysis') still available?

Any assistance much appreciated.

Thanks,




Stewart Wallace