On Monday, February 9, 2015 at 11:54:41 AM UTC+1, la gleki wrote:
2015-02-08 4:34 GMT+03:00 ianek
<jan...@gmail.com>:
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.
Sure! Because English parsers lack the ability to find something common in all of the parse trees.
No. It's because words in an English sentence can be parsed as different syntactic structures. That's what parsing means: determining structures formed by words. Not "finding something common".
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.
It specifies to which head a clause should attach. And since it's {mo'e zo'e} it's vague to which head it attaches. If the parser you use doesn't allow for that the only thing that can be done is to provide several possible trees.
It's a feature of a language, not a parser. If English had a pronoun, say, 'lar', which would mean 'the subject or the object of the main sentence', you could say "Fred saw a plane as lar flew over Zurich", which would be ambiguous semantically, but not syntactically.
{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.
If you applied {mo'e zo'e} to the English sentence you will still get the only syntax tree.
You can't "apply" {mo'e zo'e} to the English sentence, because it's not there. Likewise you don't "apply" {mo'e zo'e} to the Lojban sentence. You just parse it, because it's there.
In English you can have phrases like 'X of Y of Z' which could be parsed as '(X of Y) of Z' or 'X of (Y of Z)'. In Lojban it's not possible, but you can say ''either (X of Y) of Z or X of (Y of Z)", which is not syntactically ambiguous. You can't apply "either... or" to the English sentence, because you can't parse words which aren't there.
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.
You may invent a Lojban parser that won't be able to parse {mo'e zo'e}. Then you will need workarounds to output several trees.
XI clauses have an ambiguous syntax, so I don't see how I'd need workarounfds and several trees. Of course, I could invent a Lojban parser that won't be able to parse anything, but what's the point? {mo'e zo'e} from the parser's view is just MOhE KOhA. If I can't parse it, then I have an incomplete parser.
What you mean sounds rather like a semantic analyzer, which is extremely hard for any language, including Lojban.
mu'o mi'e ianek