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prologlogic-programming

Is it possible to view all implications of a given predicate being true or false?

I am trying to build a machine which can answer user-given questions but I have a problem which I don't know how to resolve, it boils down to the following:

Imagine the following program:

friendlycat(X)  :- cat(X), friendly(X).
cat("Felix").

We want to know if Felix is a friendly cat, so we use friendlycat("Felix"). The problem is that we, the programmer, don't know if Felix is a friendly cat or not. Is there a way to automatically see the implications if friendly(X) would be true of false given a certain X?

For example, can we get output which looks like this?

Felix (friendly("Felix") = True)
False (friendly("Felix") = False)
Solution

  • I recommend you check out Constraint Handling Rules (CHR).

    This may be your best bet to quickly reason about such constraints and their implications.

    For example:

    :- use_module(library(chr)).

:- chr_constraint cat/1, friendly/1, friendlycat/1.

cat(X), friendly(X) ==> friendlycat(X).

    Sample queries:

    ?- cat(felix), friendly(felix).
cat(felix),
friendly(felix),
friendlycat(felix).

?- cat(X), friendly(X).
cat(X),
friendly(X),
friendlycat(X).