Re: [lojban] the myth of monoparsing

On Friday, February 6, 2015 at 8:13:30 AM UTC+1, la gleki wrote:

2015-02-04 15:45 GMT+03:00 v4hn <m...@v4hn.de>:
On Tue, Feb 03, 2015 at 11:42:32AM +0300, Gleki Arxokuna wrote:
> "Fred saw a plane flying over Zurich" can have several meanings

Yes.
However, for me, the issue here is that we (hopefully..) agree
that there are different parse trees (which yield the different meanings).

No, several trees arise after you interpret the sentence.

But if you had an English parser, it would yield several trees without any interpreting. Like this:

"Fred saw a plane flying over Zurich"
NAME VERB-PAST ARTICLE COUNTABLE-NOUN VERB-ING PREPOSITION NAME

Some (much simplified) rules could be:

Sentence ::= Noun-Phrase Verb Noun-Phrase
Sentence ::= Noun-Phrase Verb Noun-Phrase Adverbial-Phrase
Noun-Phrase ::= NAME | ARTICLE COUNTABLE-NOUN | Noun-Phrase VERB-ING Prepositional-Clause
Verb ::= VERB-PAST
Adverbial-Phrase ::= VERB-ING Preposition-Clause
Preposition-Clause ::= PREPOSITION Noun-Phrase

This simple grammar yields two parse trees for that sentence:

Sentence
----Noun-Phrase
--------NAME
------------Fred
----Verb
--------VERB-PAST
------------saw
----Noun-Phrase
--------Noun-Phrase
------------ARTICLE
----------------a
------------NOUN
----------------plane
--------VERB-ING
------------flying
--------Prepositional-Clause
------------PROPOSITION
----------------over
------------Noun-Phrase
----------------NAME
--------------------Zurich

Sentence
----Noun-Phrase
--------NAME
------------Fred
----Verb
--------VERB-PAST
------------saw
----Noun-Phrase
--------Noun-Phrase
------------ARTICLE
----------------a
------------NOUN
----------------plane
----Adverbial-Phrase
--------VERB-ING
------------flying
--------Prepositional-Clause
------------PROPOSITION
----------------over
------------Noun-Phrase
----------------NAME
--------------------Zurich

Formal grammars for natural languages do exist, although they're not perfect, but the problem with multiple grammatically sensible parses (often millions of trees and more) is much greater than the problem with nonsensible trees or correct sentences that don't parse at all.

Lojban was carefully designed to avoid this problem. And it doesn't have anything to do with {xi PA}. The Lojban grammar specifies XI clauses unambiguously. Parse trees are unique. Monoparsing is not a myth. XI clauses may add semantic ambiguity on a different level then, say, simple {zo'e}, but it doesn't have anything to do with syntactic ambiguity. {la fred pu viska lo vinji do'e lo se xi vei mo'e zo'e nei poi vofli ga'u la tsurix} has only one syntax tree, regardless of the number of possible semantic interpretations.

In English you can have sentences that are semantically ambiguous due to syntactic ambiguity. In Lojban you can have sentences with (roughly) the same semantic ambiguity as the English ones, but syntactically unambiguous.

> {la fred pu viska lo vinji do'e lo se xi vei mo'e zo'e nei poi vofli ga'u
> la tsurix}

camxes only produces one parse tree for that.

And for English you don't provide any parses at all.
May be someone should just parse the original English sentence as camxes does for Lojban one?
I won't be surprised if such parser for English doesn't exist since those who write them might mix parsing and interpretation of it. The latter would be replacing {mo'e zo'e} with some PA which will immediately lead to several syntactic trees.

So I both disagree and agree with you on whether English sentence has several syntactic trees. If using one term for two operations is stopped the contradiction disappears.

If you think it should produce more then one, raise a bug report.

I'm not aware of any Lojban parsers that perform interpretation operation. In most cases you just need context and one interpretation. But this is semantic analysis. Producing all possible syntactic trees is a task needed more seldom.

Camxes is intended to produce all possible syntactic trees, and there's only one of them for any valid sentence.

mu'o mi'e ianek