From: Matthias Blume (find@my.address.elsewhere) Subject: Re: [OT] Finns and education Newsgroups: comp.lang.scheme Date: 2004-09-03 09:33:55 PST richter@math.northwestern.edu (Bill Richter) writes: > Matthias Blume responds to me in message news:... > > > That's fine if you find it uninteresting & trivial. But if you > > agree that this joke semantics has a compositional definition, > > then you seem to be agreeing with me on the point we've been > > arguing about, and disagreeing with Will. > > No. Will does not disagree with that. After all, he is the one > who suggested the "add a new start symbol" solution first. > > Sure sounds false, Matthias. What do think Will meant by the > insulting name of his thread "why Bill-semantics is not DS"? Surely > his point was that the "add a new start symbol" semantics (not due to > me) is not compositional. He certainly acted like that's what he > believed. And yet you, Lauri & I seem to all agree that "add a new > start symbol" semantics is compositional. And yet you keep insisting > you're in no contradiction to Will, and Lauri won't note it either. > What do you think we've been arguing about for 3 months now? Surely > it's whether you can turn OpS into compositional DS. Arghhh! DS != compositional Just because you define some function (which happens to be the identity function, no less) in a compositional manner you don't get a denotational semantics just by then weaving that function into an operational semantics (which was defined earlier, and unarguably in a non-compositional manner). > It's a choice to define compositionality as a property of the > function definitions. No, it is NOT a choice. > It's a choice that C-F did not make. it's a perfectly good choice, > but it's not forced on us. Here's 2 possibilities: > > The sem functions E_i are Bill-compositional if there exist functions > f_ij satisfying some equations with the E_i. > > A denotational definition of the sem functions E_i is a collection of > functions f_ij s.t. the E_i are defined by structural induction by > the f_ij. That is, the E_i are the unique functions whose existence > is guaranteed by Schmidt's Thm 3.13, given the f_ij data. > > That's 2 different types of definitions of compositionality. No. Only the second is a definition of compositionality. The first is your own invention. And if we take the liberty of changing the grammar of the language, the first definition is also meaningless as it makes all functions on syntax trees compositional. That fact alone should tell you that it is not a "perfectly good choice". > To witness: Not only have I understood your E_i, I have also given > a "better" version of them which can do without mucking with the > grammar of the language. (Again, all this is assuming you got the > details right.) Do you really think it is possible that I have not > understood your E_i? > > Sure I do, and I don't agree your version is better. Just because you > think your version is better doesn't mean you understand mine. I > can't rule out of course that you actually understand my E_i. Have /you/ understood /my/ version? Last time you said you can't read the ML code... So my conjecture, with all due respect (is there any respect due here anymore?), is that it is you who does not understand what I wrote, not the other way around. > To me, that's the right way to think of OpS: make a > total semantic function out of it, and then why not prove > compositionality? It's a fact about the OpS we might have missed. Please, dear god! In your framework this is a "fact" about *every* function. It hasn't been missed. It has merely not considered worth any attention because it is such a triviality, because it buys absolutely nothing. > That operational semantics itself is not defined in a compositional > manner. > > Sure, but that's irrelevant, as you seem to understand, but hardly > anyone else here does. No, that is NOT irrelevant! It is the crux of the joke that you don't get. > > As a matter of fact, for *every* function whose domain is the > > set of abstract syntax trees of a language there is a > > compositional definition if you take the liberty of changing > > the grammar -- as you did. > > > > That's actually not what I did, that's what Will did, but we can > > ignore this. I changed the grammar in a different way. > > Read what I wrote! You changed the grammar. Period. If one is > allowed to change the grammar, one can also do so in the far > simpler way that Will suggested. > > Fine! Doesn't mean you understood my semantics though. Indeed, it does not mean that. It also does not mean that I didn't. Will you, please, stop confusing "understanding" with "agreeing"?!? Has it ever occured to you that if everybody around you disagrees with you, chances are that /you/ are the one in the wrong? > I like my semantics, and happen to also think it's compositional. Fine. Can you now take this great semantics of yours and vanish from this group? Thanks. Matthias