[Bug 5418] conformance criteria: "valid if" vs "valid if AND ONLY IF"

http://www.w3.org/Bugs/Public/show_bug.cgi?id=5418


johnarwe@us.ibm.com changed:

           What    |Removed                     |Added
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           Keywords|                            |needsAgreement




------- Comment #2 from johnarwe@us.ibm.com  2008-01-25 20:55 -------
wrt [1], if and only if, the issue is one for the logicians and/or spec
lawyers.  As written, following the formal rules of logic for implication, and
taking the "model valid" sentence as an example, we have today:
"A conforming SML model is valid if it satisfies all of the following
conditions:".  According to the formal definition of implication, this sentence
does not assert its converse.  That is, it does NOT say "A conforming SML model
is INvalid if it FAILS TO satisfY ANY of the following conditions:"... it says
nothing about this case.

One way to phrase the question would be to say: do we want to leave the
converse results unstated, or not?  An assertion was made, IIRC by Sandy, that
at least one of them should be changed from implication (if/then) to
equivalence (if and only if) so the converse cases are covered.  We did not
discuss this to the point of full wg consensus however, hence there is no
concrete proposal in the bug yet.  The wg as a whole should feel free to make
one.

Received on Friday, 25 January 2008 20:55:16 UTC