[dcgreenwood]

Is there a simple way using backtracking to find a match between a set of variables and a database of facts where the match may not be perfect?
For example

Code: Select all

domains
        myDomain : good; bad ; ok.
class facts
        myFactDB : (myDomain VarA, myDomain VarB, myDomain VarC, myDomain VarD).
 
%assume I have a database of myFactDB with different combinations of the variables, but not all possible combinations   
        
predicates
        findMatch(myDomain VarA, myDomain VarB,myDomain VarC,myDomain VarD).
        
clauses
        findMatch(VarA,VarB,VarC,VarD):-
        myFactDB(VarA,VarB,VarC,VarD.
        

Assuming I got my syntax right, this should find the database entry that matches VarA,VarB,VarC,VarD. But how can I approach writing a clause that will find a match of 3 of the 4 variables, if there isn't a perfect match? I can think of how to do it with separate clauses with all combinations of one or more of the variable set as anonymous, but is there any other way? Should I try something other than a fact database, such as lists?

[Harrison Pratt]

Code: Select all

domains
    myDomain = good; bad; ok.
    myDomainList = myDomain*.
 
class facts
    myFactDB : (myDomain VarA, myDomain VarB, myDomain VarC, myDomain VarD).
 
class predicates
    getMatchN_nd : (integer Count, myDomainList TestList) -> myDomainList MatchingValues nondeterm.
clauses
    getMatchN_nd(N, TestList) = FactValues :-
        myFactDB(VarA, VarB, VarC, VarD),
        FactValues = [VarA, VarB, VarC, VarD],
        list::length(list::intersection(FactValues, TestList)) >= N.  % want at least N matches
 
clauses
    run() :-
        write("\n\n", "Testing", "\n\n"),
        NumWant = 1,
        ValuesWant = [good, good, ok],
        assert(myFactDB(good, good, bad, ok)),
        assert(myFactDB(bad, bad, bad, ok)),
        assert(myFactDB(good, bad, good, bad)),
        MM = getMatchN_nd(NumWant, ValuesWant),
        stdio::write("\nWrite matched ", NumWant, " of ", MM),
        fail.
    run() :-
        write("\nFAILED\n"),
        _ = readLine().

[dcgreenwood]

Thanks, I'll use that!

[Gukalov]

Code: Select all

implement main
    open core
 
domains
    myDomain = good; bad; ok.
 
clauses
    run() :-
        L1 = [ good, good , bad, ok ],
        L2 = [ bad, bad , good, ok ],
 
        L3 = list::intersection(L1, L2),
        console::write("Intersection12 = ", L3, "\n"),
 
        L4 = list::intersection(L2, L1),
        console::write("Intersection21 = ", L4, "\n"),
 
        L5 = [ X || tuple(X, X) = list::zip_nd(L1, L2) ],
        console::write("Real matches = ", L5, "\n"),
 
        _ = console::readChar().
 
end implement main
 
goal
    console::runUtf8(main::run).
 
%Intersection12 = [good,good,bad,ok]
%Intersection21 = [bad,bad,good,ok]
%Real matches = [ok]