Re: [Sigmakee-develop] Problems pre-processing suo-kif sentences

[Cameron R. <cr...@sy...>]

Hi Adam,

My test client code below calls Formula.preProcess() which fails at line 
758 (not shown).  I'll have to review unification and how it relates to 
the holds predicate.  Thanks for the info.

Cheers,
Cameron.

Adam Pease wrote:
> Hi Cameron,
>   Which is line 758 in the code segment below?
>
>   All clauses get an added "holds" predicate.  In that way, the query
>
> (?REL A B)
>
> will unify with
>
> (rel A B)
>
> because they are preprocessed to
> (holds ?REL A B)
> (holds rel A B)
>
> If (rel A B) weren't preprocessed, you'd have
>
> (holds ?REL A B)
> (rel A B)
>
> and they wouldn't unify.
>
> Adam
>
> Cameron Ross wrote:
>> Hi Adam,
>>
>> I'm analyzing Sigma's Formula.preProcess() method as I build a 
>> SUO-KIF translator for the PowerLoom system.   I have the following 
>> questions:
>>
>> 1) The SUO-KIF BNF indicates that (?a b c) is a valid sentence.  
>> However, the following code generates a NullPointerException at line 
>> 758 of Formula.preProcess():
>> /        Formula formula = new Formula();
>>         formula.read("(?a b c)");
>>         List<Formula> lst = formula.preProcess();
>> /              Either "(?a b c)" is not a valid suo-kif sentence 
>> (i.e. I'm misinterpreting the grammar), or there is a bug in 
>> Formula.preProcess().  Any ideas?
>>
>> 2)  If I pre-process the sentence "(a b c)" I expect "(a b c)" but 
>> get "(holds a b c)".  Isn't the 'holds' predicate to be introduced 
>> when there is a variable in the predicate position?  That is, "(?a b 
>> c)" pre-processes to "(holds ?a b c)".  Perhaps I'm missing something 
>> fundamental with how Vampire expects input.
>>
>> Cheers,
>> Cameron.
>>
>>
>>
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>