Hi,
It takes a lot of guts to related SLD failure of
an empty predicate to CWA:
closed-world assumption
The assumption that what cannot be proved
true is false. Therefore, sending a message
corresponding to a declared but not defined
predicate, or calling a declared predicate
with no clauses, fails. But messages or
calls to undeclared predicates generate an error. https://logtalk.org/handbook/glossary.html#term-closed-world-assumption
I mean all he wants to say is that an empty
predicate doesn't have a throw catchall clause.
Nothing to do with CWA. CWA is a mathematical
concept postulating that from G |/- A we want
to jump to G |-_CWA ~A. Its not that the
predicate in questions would be called with
a negation in front, and that we would really
be interested in a "is false".
Even if SWI has rebranded "fail" into "false"
in the top-level, its still most often
a SLD result, and not a CWA result.
At least the key phrase still uses "fails",
when he writes "calling a declared predicate
with no clauses, fails". It could be worse
if he would really apply the CWA and write
calling a declared predicate with no clauses,
is false". Such a conclusion can only be
detected in logic by querying ~A, while he
still deals with a query A.
Bye
Hi,
How it started:
https://www.instagram.com/p/Cump3losObg
How its going:
https://9gag.com/gag/azx28eK
Bye
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