From: Aditya Kalyanpur <swap_adityak@yahoo.com>

Date: Tue, 5 Apr 2005 15:29:08 -0700 (PDT)

Message-ID: <20050405222908.85221.qmail@web52710.mail.yahoo.com>

To: public-rdf-dawg@w3.org

Date: Tue, 5 Apr 2005 15:29:08 -0700 (PDT)

Message-ID: <20050405222908.85221.qmail@web52710.mail.yahoo.com>

To: public-rdf-dawg@w3.org

Continuing where Bijan left off, I have a comment on the formal definition of "Optional Matching". Here's what the specs [1] say: "Given graph pattern GP1, and graph pattern GP2, Opt(GP1, GP2) is the optional match of GP2 of graph G, given GP1. Let GP = (GP1 union GP2) then S is a solution of Opt(GP1, GP2) if" [snip] ----- I'm not sure which "union" is meant here? Obviously, I assume we don't mean the 'union' keyword used for pattern alternatives. In any case, "union" implies logical disjunction whereas what we need here is a conjunction, i.e., we need a group pattern, so we can rewrite GP = {GP1, GP2} ---- ..continuing with the defn.. "S is a solution for a match of GP on G, or else S is a solution for GP1 and S is not a solution for GP. S in R(Opt(GP1, GP2), G) if: S in R(GP, G) or S not in R(GP,G) and S in R(GP1, G)." ------ I'm not sure if "S not in R(GP,G)" is required in the second disjunct. As I understand Optional Matching, if S is a solution to an optional match of GP2 on G given GP1, it implies that S must match GP1 first (on G) and then optionally match GP2 (on G), right? So in that case, the definition should be: S in R(Opt(GP1, GP2), G) if: S in R(GP1, G) or S in R(GP, G), where GP = {GP1, GP2} ------ Cheers, Aditya [1] http://www.w3.org/2001/sw/DataAccess/rq23/defns.html __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.comReceived on Tuesday, 5 April 2005 22:29:10 GMT

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