From: Axel Polleres <axel.polleres@deri.org>

Date: Mon, 15 Jun 2009 19:43:24 +0100

Message-ID: <4A36964C.6040105@deri.org>

To: Jos de Bruijn <debruijn@inf.unibz.it>

CC: Christian De Sainte Marie <csma@fr.ibm.com>, RIF <public-rif-wg@w3.org>

Date: Mon, 15 Jun 2009 19:43:24 +0100

Message-ID: <4A36964C.6040105@deri.org>

To: Jos de Bruijn <debruijn@inf.unibz.it>

CC: Christian De Sainte Marie <csma@fr.ibm.com>, RIF <public-rif-wg@w3.org>

Jos de Bruijn wrote: > Sorry, I cannot deal with this discussion right now. I commented on the > proposal and said what I think is the best way forward. I leave it up to > the editors of the Core document to decide how to proceed. I will try to jump in, but can't do anything before late tonite, unfortunately. Axel > On 15 Jun 2009, at 15:01, Christian De Sainte Marie <csma@fr.ibm.com > <mailto:csma@fr.ibm.com>> wrote: > >> >> Hi Jos, >> >> Thanx for the comments. >> >> Can I infer that the bottom-up definition is equivalent to yours, once >> all your comments are taken into account? >> >> Responses to yu comments are in-lined, below. >> >> Jos de Bruijn <debruijn@inf.unibz.it <mailto:debruijn@inf.unibz.it>> >> wrote on 15/06/2009 12:35:05: >> > >> > - the use of fonts is inconsistent. Sometimes you use two different >> > fonts (e.g., times and teletype) to refer to the same thing (e.g., b in >> > the definition of rule safeness) >> >> Easy to fix: that is only typography. >> >> > - The transformations 1 and 2 are not specified in sufficient detail. >> >> Can you point more precisely where they are ambiguous and need be >> specified in more detail? >> >> > This is easy to fix; they essentially mean to do the same thing as the >> > collection B_psi I defined. In fact, I guess rewriting to disjunctive >> > normal form is probably easier to understand for many readers than the >> > tree decomposition I defined. Of course, it needs to be specified. >> >> Do you mean that we need to specify the rewriting to DNF? Isn't >> pointing to a textbook enough? I mean, is not that considered basic >> knowledge? >> >> > - in the definition of bound, it is unclear what f\e and f\a are. >> >> Yep. Laziness... Easy to correct, though: it means conjunction, f, >> minus the conjunct, e (or a), of course. >> >> > - there is unnecessary duplication between the definitions of >> > boundedness in atomic formulas and conjunctions; these two definitions >> > should be compounded. This is the reason I compounded them in the first >> > place. >> >> Well, of course, this is feasible. It just seemed eaiser to read and >> understand if the two cases where handled separately (variable-free >> and variables bound elsewhere in the formula). >> >> An easy fix, that does not require the introduction of equivalence >> classes or whatever, is to describe only the conjunction case, and say >> that an atomic formula is handled as a conjunction with a single >> conjunct. >> >> > - the notion of labeled positions in binding patterns is not defined >> >> Laziness again: as you probably guessed, it was shorthand for "...the >> i-th postion in the binding pattern is 'u'..." (or 'b', whateber). >> Easy to correct, too. >> >> > - what is an equality formula involving two variables? is ?x=f(?y) one? >> > This needs to be clarified. >> >> "Equality involving two variables" is something I copied from your >> definition... I understood that it meant that the term on each side of >> the equality was a variable. It can be made precise easily, of course. >> >> > - the terminology used for rules is not in line with the definitions in >> > BLD (e.g., a fact is not a rule) >> >> Did you read the latest version, after I took Stella's comment into >> account? The terminology is that of BLD, I think. >> >> > - in general, the symbols you use are not in line with the symbols we >> > use for rules and condition formulas >> >> I do not understand the comment: can you explain what are "the symbols >> we use for rules and condition formulas"? >> >> > - safeness of document and group formulas can be written more concisely, >> > see the way I defined them >> >> Your definitions are, indeed, more concise, but they seemed ambiguous, >> to me, which is why I completed them: >> - you omit the case of an empty group (without saying whether it is >> safe or not), >> - and you say nothing about imports (is a document that contains a >> safe group but that imports a document that contains an unsafe one >> safe?). >> >> But I may be wrong. If your definitions are not ambiguous, of course, >> they should be used. >> >> > - in the definition of safeness you forget to do the rewriting to >> > disjunctive normal form >> >> I do not understand what you mean. The text says that "the definitions >> of /boundedness/ and /safeness/, below, apply to a condition formula, >> /f/, after it has been simplified syntactically ..." >> >> Do you mean that it should be repeated befor ethe definition of safeness? >> >> > - it is unclear what is meant with "bound within the scope of their >> > respective quantifiers" >> >> Is it? How would you say that each existentially quantified variable >> must be bound in the formula that is in the scope of its quantifier? >> >> > I think the best way to proceed is to change the definition that are >> > currently in Core to bring them in line with the kind of definition I >> > think you want, by doing the following: >> > [...] >> >> If you have, really, no other comments, do not you think that it is >> easier, instead, to make all the corrections that you request in the >> bottom-up definition? >> >> My point is that, if we rewrite the top-down definition the way you >> suggest, we will end up with a whole new definition again, that we >> will have to review, and from which we will have to derive the correct >> extension for PRD, whereas, with your and Stella's review of the >> bottom-up definition, we have one that seems to be correct and >> sufficient for our purpose, and for which we have a very simple >> extension for PRD... >> >> What do you think? >> >> Cheers, >> >> Christian >> >> ILOG, an IBM Company >> 9 rue de Verdun >> 94253 - Gentilly cedex - FRANCE >> Tel. +33 1 49 08 35 00 >> Fax +33 1 49 08 35 10 >> >> >> >> Sauf indication contraire ci-dessus:/ Unless stated otherwise above: >> Compagnie IBM France >> Siège Social : Tour Descartes, 2, avenue Gambetta, La Défense 5, >> 92400 Courbevoie >> RCS Nanterre 552 118 465 >> Forme Sociale : S.A.S. >> Capital Social : 609.751.783,30 € >> SIREN/SIRET : 552 118 465 02430 >> -- Dr. Axel Polleres Digital Enterprise Research Institute, National University of Ireland, Galway email: axel.polleres@deri.org url: http://www.polleres.net/Received on Monday, 15 June 2009 18:44:04 UTC

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