• November 6, 2006
    Version 1.3 of BB1 released. Couple of bug fixes. New versions of semLexHole.pl, alphaConversion.pl, betaConversion.pl and betaConversionTestSuite.pl.

  • November 5, 2006
    Arguments are swapped in the macro for transitive verbs in semLexHole.pl in version 1.2 of BB1. Corrected macro:

    semLex(tv,M):-
       M = [symbol:Sym,
            sem:lam(Z,lam(X,app(Z,lam(Y,lam(H,lam(L,and(pred2(L,Sym,X,Y),leq(L,H))))))))].
    
    Reported by Mike White.

  • November 17, 2005
    Added link to interview with Patrick Blackburn in PhiNews

  • September 9, 2005
    Discovered bug in alphabeticVariants/2. Some formulas with identical free variables were wrongly classified as non-alphabetic variants. The revised code for this predicate is:

    alphabeticVariants(Term1,Term2):-
       alphaConvert(Term1,[],[]-Free1,Term3),
       alphaConvert(Term2,[],[]-Free2,Term4),
       Free1==Free2,
       numbervars(Free1,0,N),
       numbervars(Term3,N,M),
       numbervars(Term4,N,M),
       Term3=Term4.
    

  • September 8, 2005
    There appears to be a bug in betaConvert/3. For input such as app(app(X,Y),Z) it returns no rather than succeeding and returning the same term. The current solution is this code:

    betaConvert(X,Y,[]):-
       var(X), !,
       Y=X.
    
    betaConvert(Expression,Result,Stack):-
       nonvar(Expression),
       Expression = app(Functor,Argument),
       alphaConvert(Functor,Converted),  
       betaConvert(Converted,Result,[Argument|Stack]), !.
    
    betaConvert(Expression,Result,[X|Stack]):-
       nonvar(Expression),
       Expression = lam(X,Formula),
       betaConvert(Formula,Result,Stack), !.
    
    betaConvert(Formula,Result,[]):-
       nonvar(Formula), !,
       compose(Formula,Functor,Formulas),
       betaConvertList(Formulas,ResultFormulas),
       compose(Result,Functor,ResultFormulas).
    
    betaConvert(Exp,app(Exp,Y),[X]):-    
       betaConvert(X,Y).
    
    Thanks to Sebastien Hinderer and Carlos Areces for reporting this.

  • August 8, 2005
    Version 1.2 of BB1 released. Deals with the problem of numbervars in fol2otter.pl, fol2bliksem.pl, fol2tptp.pl, and comsemPredicates.pl. Also fixed a bug to do with equality in backgroundKnowledge.pl.

  • July 9, 2005
    There is a problem with numbervars when using newer versions of SWI Prolog. Thanks to John Rood for reporting this.

  • June 10, 2005
    Version 1.1 of BB1 released. Major changes in the perl programs.

  • March 15, 2005
    Representation and Inference now available at CSLI publications.