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Re: ISSUE-82 (Unification): Shall Core limit unification to pattern matching (as PRD does)? [Core]

From: Dave Reynolds <der@hplb.hpl.hp.com>
Date: Tue, 25 Nov 2008 17:32:21 +0000
Message-ID: <492C36A5.4040007@hplb.hpl.hp.com>
To: Christian de Sainte Marie <csma@ilog.fr>
CC: Gary Hallmark <gary.hallmark@oracle.com>, Rule Interchange Format Working Group WG <public-rif-wg@w3.org>

Christian de Sainte Marie wrote:
> 
> Gary Hallmark wrote:
> 
>> [...]
>>
>> RS3:
>> ex:A(2)
>> ex:A(?x) :- ex:A(?y), ?y + 1 = ?x
>>
>> [...]
>> RS3 is unsafe, so if PRD adopts Core safety then RS3 would not be in 
>> PRD, even though it poses no problems.
> 
> Is RS3 unsafe? Is it because = is meant as pred:numeric-equal? But it 
> poses no problem from the logic point of view either, right?

RS3 is supposed to be safe, ?y occurs in a plain atomic formula.

Though looking at the current definition of safeness we don't seem to 
have covered equals properly.

Dave
Received on Tuesday, 25 November 2008 17:33:48 GMT

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