Subject: Re: [xsl] Testing 2 XML documents for equality - a solution From: Mukul Gandhi <mukul_gandhi@xxxxxxxxx> Date: Thu, 31 Mar 2005 04:36:32 -0800 (PST) |
Hi Dimitre, I am really not good at mathematics at this level. I did studied about relations like "symmetric, reflexive and transitive" time back. But I did so just to score grades. I had no idea then their practical use.. It is indeed enlightening for me to know they have real practical use (in XML & XSLT!). I cannot define my problem in these terms.. As my knowledge is limited. I would be happy if you can define in these precise terms the problem I am trying to solve(based on my earlier posts to this thread). I'll keep it as a reference for future use. I defined the problem (I am trying to solve) from an average programmer's point of view.. And I think that it is quite understandable to an average programmer ;) Regards, Mukul --- Dimitre Novatchev <dnovatchev@xxxxxxxxx> wrote: > > We are in a vicious circle here. You explain one > undefined notion > ("document equality") with two other undefined terms > ("identical node > structure" and "abstract structure")... > > Whenever one defines "equality", this means a > symmetric, reflexive and > transitive relation on the set of X^2 of pairs of > values from a set X. > > One *must* define a breakdown of X^2 into classes of > equivalence > (non-intersecting subsets of X^2 that cover X^2 > completely (to put it > in other words: whose union is X^2) ) . Then, by > definition, every > pair of elements belonging to a class of equivalence > are considered > equivalent. > > Without doing this, one cannot speak about > "equality" at all. There > are cases when more than one breakdown into classes > of equivalence may > exist on the same set (e.g. the classes of > equivalence on the set of > natural numbers N may be defined as all k+1 sets of > numbers {x mod k = > r, where r = 0, 1, ..., k-1} In this case there are > an infinite number > of different equivalent relations on N^2, just let k > vary from 2 to > infinity). This example shows clearly that if you > haven't defined > precisely about which equivalence relation you are > speaking, then you > have no equivalence relation at all. > > In this concrete case "document equality" remains > undefined. > Therefore, the problem based on it is also > undefined. Any activity to > solve an undefined problem is groundless and > imaginary -- something > like hallucination. > > > Cheers, > Dimitre. __________________________________ Do you Yahoo!? Yahoo! Small Business - Try our new resources site! http://smallbusiness.yahoo.com/resources/
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