R A Brown, On 23/04/2012 13:46:
> The point is that _parsing_ a postfix expression inorder to
> evaluate it is utterly pointless. How this would apply to
> language generally and not the narrow domain of mathematical
> expressions is IMO more controversial and more of a
> challenge to those who want to try it.

It's a challenge not just in finding a solution to a defined problem but rather in finding a coherent characterization of the problem in the first place. A processor that can do the semantic equivalent of mathematical evaluation looks to me like it's not linguistic. To linguists and philosophers who believe that syntax (i.e. the Meaning end of sentence structure) is written in the Language of Thought, then I guess the idea would make sense, with the parser evaluating in the LoT as it goes along. But I myself don't believe that language has access to LoT, and of course even if one did, one has scant idea of what it's like, and so can't base a conlang on it.
  
> We generally understand language as we hear it or read it -
> tho what goes on the mind is quite remarkable and AFAIK not
> properly understood. But many of us have properly met
> occasions where some sort of analysis or parsing has been
> necessary. I recall many years ago when I was researching
> for my M.Litt degree, coming across a sentence in a German
> book that went on and on and on. There was - and I don't
> exaggerate - a full half-page of text before I met the
> full-stop (period). I was completely lost and the only way
> I could make sense of the thing was to take the long period
> apart and construct what, in effect, was a rough & ready
> parse tree.

That's right. Sometimes our parsing happens at a conscious level. That's rare, though, of course; usually parsing is done automatically and unconsciously.
  
>> In this discussion I had been abstracting away from the
>> fact that the input to the parser is phonological (i.e.
>> stuff that is phonetically interpreted) and the output is
>> syntactic (i.e. stuff that is semantically interpreted).
>> I mention this in case that abstraction created
>> confusion, and you took me to be claiming that the
>> eventual output of the parser is a mere structuring of
>> phonological forms.
>
> Not at all - the input is phonological (or, as you say,
> written form which represents the phonological input) and
> the output is stuff that is semantically understood. As far
> as I see we are basically in agreement here.
>
> But I deliberately avoided including the word 'syntactic'
> because, I think, this is where the problem lies. To move
> from the input to the output some sort of syntactic parsing
> or pattern matching or something) is needed in the case of
> human language. How this is done is another matter and not
> really relevant to this discussion - but we both agree that
> parse trees are useful devices in demonstrating this.

A syntactic tree contains semantically interpreted relations between semantically interpreted lexical nodes -- the syntactic tree is what makes sentence meaning a coherent whole, rather than just a jumble of word meanings.

So psychologically implemented language must involve a parser that (when hearing) outputs a syntactic tree -- input is phonological structure, output is syntactic structure.

I wonder if "parse tree" means something different, something more tied up with the parsing algorithm or process?
  
>> I assume that parsing of all languages, including Fith,
>> takes a sequence of phonological forms as input and
>> outputs a (semantically interpretable) syntactic tree.
>
> If you are going to _parse_ Fith, then you can, if you wish,
> out put a parse tree - but this should be a waste of time.
> The point is that Fithians do not need any parsing (or
> similar) process to go on in their minds as each understands
> what the other says, i.e. as Fithian A speaks, Fithian B
> receives the input and understands it as A speaks by simple
> stack manipulation in its mind and by nothing else.

To me, 'parsing' in a psycholinguistic context means no more than what the hearer has to do in order to get from the phonological input to the syntactic outpur. Even if that could be done with a stack alone (as I think is possible), it would therefore count as parsing. I don't mean to oblige you to use 'parsing; in a similarly broad way; I just note it to avoid potential misunderstanding.

It might be that Fith sentence-syntax is in the Fith Language of Thought, in which case the parser can go straight to semantic 'evaluation' like the arithmetic example you gave. If this is the case, then that'd be the specialest thing about Fith, and Fith would not be human-speakable. The FIFO aspect of Fith would be rather secondary.

But if that's not the case, then the process that combines two items into oneis by definition a process that builds up the syntactic tree.
  
> A syntactic tree is just that - a tree which demonstrates
> the syntactic structure of the utterance. It tells us, in
> itself, nothing about what is _meant_. It is true, such a
> tree may help understanding a difficult or abstruse sentence.

This is one source of our misunderstanding. I take the view that the main job of the syntactic structure of a sentence is to tell us something about what is meant. Syntax is what makes the difference between a jumble of word meanings and a single integrated proposition.

> But, as I understood Jeffrey, the Fith experiment was to
> produce a language in which evaluation, i.e. comprehension
> of meaning, would be possible by beings whose brain
> supported only stacks as the reasoning process.

As I said above, if Fith syntax is written in Fith Language of Thought, then the parser can evaluate as it proceeds. But otherwise, the operation performed by the stack would amount to the construction of a syntactic tree.

>> Take the sentence "zhong hong non zhong hong lo krai" =
>> "man nation without man nation with hates" = "Man without
>> nation hates man with nation". There are no stack
>> conjunctions in this, and I understood "non" to be an
>> operator, with operands "zhong" and "hong", and "lo" to
>> be an operator, with operands "zhong" and "hong", and
>> "krai" to be an operator with operands "zhong hong non"
>> and "zhong hong lo".
>
> Yes - "zhong hong non zhong hong lo krai" is, in fact,
> nothing more than an example of a SOV object language with
> postpositions - not exactly uncommon among human languages!
>
> If this is all that Fith was then, indeed, I would agree
> that it is nothing remarkable. But the sentence you give,
> altho grammatical Fith, is an example Jörg's 'Shallow Fith',
> see:
> http://www.langmaker.com/shallowfith.htm
>
> Of it, Jörg wrote:
> {quote}
> Shallow Fith is an interlanguage humans and Fithians could
> use to communicate with each other. Basically, it is a
> proper subset of Fith, with strict limits to stack depth and
> with most of the stack operators removed. The Shallow Fith
> sentences could be parsed as SOV/postposition/noun-adjective
> sentences by humans and as very simple LIFO sentences by
> Fithians.
>
> *We are leaving the ground of Jeffrey Henning's original
> creation here*; this is my own invention .....
> {unquote - emphasis is mine}

I think the limits to stack depth are superfluous, but the removal of most stack operators is necessary for the grammar to be human-usuable.

Is there a difference between Fith for humans and Fith for Fithians? Only, IMO, if Fith syntax is in Fithian LoT. I don't see that FIFO has a bearing on things.

>>>> Fith looks to me like it has RPN syntax in which a
>>>> stack builds up a tree of predicate--argument
>>>> structure.
>
> That was not, as I understood it, Jeffrey's intention. I had
> a good deal of email exchanges with Jeffrey at that time
> (tho not much of it about Fith) and met him when I visited
> Boston, so I hope I have not misunderstood him.

If Fith syntax is in Fithian LoT, the project makes a lot more sense -- it becomes much more than a RPN syntax spoken by creatures with potent working memories.  Based on what you've said, and your discussions with Jeffrey, then, I assume that the intent was indeed for fith syntax to be in Fithian LoT.

There would still be Fith myths, though: (1) that Fith is difficult for humans to speak; whereas in fact it is impossible due it falling outside the bounds of human language and human cognition; (2) that (1) is connected to LIFO.
  
>> Take the example "John snores Mary knows" (= Mary knows
>> John snores).
>
> But is a relex of "John snores Mary knows" actually valid
> Fith. The language seems to me to be in too fragmentary a
> state to give the Fith equivalent of "Mary knows John
> snores" because "John snores" is a noun clause, being the
> object of "John knows." Many (most?) languages require tat
> the be explicitly marked, i.e. Mary knows that John snores.
>
> Some, like Latin, have a special construction for the object
> clause; in the case it is the accusative and infinitive
> construction, i.e.
> Maria scit Iohannem stertere.
> May.NOM knows John.ACC to-snore
>
> We have no example of the handling of subordinate clauses in
> Fith.
>
>> "John Mary snores shen knows" means the same.
>
> No it doesn't. On
> http://www.langmaker.com/stackconj.htm
> it is quite clearly stated that:
> "shen ( n1 n2 - n2 n1 ) exchanges the stack positions of the
> top two stack items"
>
> I.e. "John Mary snores shen knows" is the equivalent of
> "Mary John snores knows" not of "John snores Mary knows."
>
> But whether any of these sentences are valid Fith (assuming
> words are relexed) is IMO doubtful.

I was only seeking an example to explain how shen creates crossing branches.

I did make a mistake, though. "John, Mary, snores, shen, knows" would be equivalent to "Mary, snores, John, knows" = "Mary's snoring knows John".

I should instead have used the example "John, Mary, shen, snores, knows", equivalent to "Mary, John, snores, knows" = "Mary knows John snores". The link from "Mary" to "knows" crosses the branch from "John" to "shen" or "snores".
  
> In summary:
> - My understanding of Fith is that it is an attempt to
> produce a language usable for beings who mental faculties
> allow nothing other than a stack structure.
> - that considerations of parse trees are not directly relevant.

my summary is:

- The syntactic tree is an integral part of (human) language.
- A LIFO processor is sufficient to parse human language if it lacks local ambiguities. (My Livagian and Artlang-1 are examples, as are many PN and all(?) RPN conlangs); the LIFO processor builds the syntactic tree.
- Fith syntax does not require semantic interpretation, because it is already written in the Fith Language of Thought; it's this, rather than the use of stacks, that makes Fith remarkable.

> If there is a "LIFO myth" and a "Fith myth" it is that:
> (a)a language could not be comprehended by an alien race
> using LIFO structure alone, and the only use of a LIFO
> structure is in the building up of parse trees.
> - that Fith is nothing more than 'Shallow Fith' (i.e. a SOV
> language with postpositions and post-posited adjectives)
> with weird 'stack conjunctions.'

I am happy to believe you about this and to agree that it is appropriate to call them myths.
  
> I maintain that
> - there is nothing per_se that makes (a) impossible (tho
> till humans meet such a race we cannot see definitely that
> it is possible);
> - that Fith was an attempt to do this, i.e its aim is to be
> rather more than (b).

... and I'm happy to agree with this too.

I had misunderstood what Fith was supposed to be.

I think the FIFO aspect of Fith is a bit of a red herring in as much as there is no connection between the FIFO aspect and its fundamental difference from human language. And Miles Forster can never learn Fith. He can, however, learn a human version of Fith (not just Shallow Fith); but by doing so, he will not prove anything unexpected.

--And.