On Mon, 22 Jun 2015, Edgaonkar, Shrirang wrote: > What is the difference ? Am I missing anything here ? \= isn't a constraint and it doesn't mean "not equal." It is a logical statement true if its operands cannot be unified. In your second example, when the interpreter attempts to satisfy STR1 \= "", at that point STR1 is a free variable. It *can* in fact be unified with "", so the statement "it is not possible to unify STR1 with "" " is false, and the goal fails. The other example worked because it was waiting until STR1 had a (ground, not free variable) value before testing it. I don't know if the not-equal constraints in any of the constraint libraries will work with strings, but that's what you need; if there isn't one ready-made, you may have to create a custom one. -- Matthew Skala mskala_at_ansuz.sooke.bc.ca People before principles. http://ansuz.sooke.bc.ca/Received on Mon Jun 22 2015 - 05:09:34 CEST
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