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Re: Stack-based human languages? (was Re: My Three Assertions)

From:Jörg Rhiemeier <joerg_rhiemeier@...>
Date:Monday, February 28, 2005, 19:38

On Mon, 28 Feb 2005 00:12:01 +0100,
Henrik Theiling <theiling@...> wrote:

> Hi! > > Jörg Rhiemeier <joerg_rhiemeier@...> writes: > > > > Isn't that just a matter of staying within 7+-2 bounds? I don't see > > > > anything inherently more difficult about the *syntax* that makes it > > > > human-incompatible. > > > > > > I think so, too. SOV and OSV syntax are just like Fithian. > > Ok, this statement was too absolute. :-) > > > I don't think so. > > Ok. > > > Fith allows a kind of stack acrobatic that goes well beyond anything > > possible in human languages, in fact going beyond what human minds > > can process in real time. The resemblance of Fith to verb-final > > human languages is only superficial. > > :-) > > Yes, the stack operations are special and crucial for distinguishing > Fith from natlangs, that's true. E.g. references to the nth stack > cell, duplication, swapping etc. are very different from how natlangs > work.
> I just wanted to state that a stack is an appropriate data structure > for many structures in natural languages. The resemblance is not > superficial, I think. Only natural languages, in contrast to Fith, do > not allow direct operations on the stack and they use it to a limited > depth.
I know about the usefulness of stacks in language parsing, yes. From a half-forgotten lecture on compiler design, I remember that they are frequently used for such purposes, even if the language parsed is not overtly stack-based like Forth or Fith. Whether the human brain uses a stack, that's another question. Certainly not in the same way as the Fithian brain. But I see what you mean.
> > > A typical > > > *long* Japanese sentence (or a long German sentence, too) uses a stack > > > quite heavily. It first pushes the nouns, then pops them with a verb, > > > pushes back the combined concepts, pushes more nouns, and finally pops > > > the rest. > > > > This is the first time I see any human language being described as > > stack-based. > > Hehe. :-) > > But you saw them described as rules like > > S -> NP VP > > right?
Yes. S -> NP VP is a nice context-free rule, it is even in Chomsky's Normalized Form. (I'll disregard the question of the validity of the VP node, here.)
> And context-free grammars (which are not enough to describe > human language, of course -- just a small excerpt from some grammars) > are equivalent to stack automata. Usually you start with a simple > approach like this to seethe real problems of natural language > processing.
> > > Only a human language has a principle limitation in both the amount of > > > words a concept can be remembered when it is not used (=life time of a > > > stack cell) and the amount of data that can be remembered at the same > > > time (=stack depth). > > > > These "limitations" are of such an importance that they render the > > stack model of little use for describing human languages of any kind, > > even verb-final ones. > > Reading my mail again I think I posed my point too radically. > I actually fully agree with you. :-)
> > > ... daß Peter Maria Rolf Essen kochen helfen sehen kann. > > > push push push push poppoppush poppoppush poppoppush poppush > > > > This is a rather contrived example. > > Yes. :) > > > Few if any German L1 speakers talk that way. > > Indeed. > > > And while a Fithian would parse it that way, I doubt that any human > > would. Human languages have tree-based structures with depth > > limitations, not stack-based ones. > > Trees are the result of parsing a language using a stack-based > machine. Fith can be parsed into such trees as well. The additional > operations for stack manipulations to co-indexing etc. are different > from what is usually needed for natural language processing, but there > is a common basis. > > Still no? :-)
Now that you have stated your case, I understand how you arrived at describing German subclauses as "stack-based". I'd not say that any human natlang is "stack-based", certainly not in the Fithian sense, though stacks are certainly useful in parsing natlangs, and perhaps each of us has some kind of stack somewhere deep in our brain ;-) Greetings, Jörg.