Given a sentence from http://home.uchicago.edu/~bartels/papers/Bartels-Johnson-2015-Cognition.pdf: We describe what can be gained from connecting cognition and consumer choice by discussing two contexts.

From a layman's perspective, "by discussing" may link to either of two former phrases contained in this sentence.

How does any school of parsing (e.g. popular ones like dependency parsing, constituency parsing, and others) preserve the ambiguous linkage of "by discussing two contexts" to both "describe" and "connecting"?

Is preserving the ambiguity only possible by suggesting two separate parses, or is there a kind of parse that, inherently, preserves the ambiguity?

  • In case there is no ambiguity under proper grammar, can you suggest a good exhaustive resource for proper English grammar?
    – matanox
    May 17, 2015 at 21:11
  • 1
    A parser can be designed to deliver all grammatical parses, and when that's done to most written English sentences, it turns out there are multiple meanings, many of them automatically discarded without consideration by humans. Further, it frequently turns out that they're not ambiguous at all when spoken. If you're dealing with English text, you rarely hafta worry about preserving ambiguities; you just hafta plow through them. A famous paper by Steve Abney explains how that works.
    – jlawler
    May 17, 2015 at 23:36
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    I find the section about ambiguities quite very informing and useful!
    – matanox
    May 18, 2015 at 1:11

1 Answer 1


No. It's a structural ambiguity, meaning there are two possible structures with differing associated interpretations. Parses are supposed to give you structures. Since there are two structures, there must be two parses.

You could invent a notation for abbreviating two partially similar parses in one diagram, I'm sure (use colored pens, e.g.), but notational magic can't change the fact there are two parses.


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