Language, Logic and Information


2 July 2021
13:00 - 14:30
Online (Teams)

NLP Reading Group Fri. 02/7: CLIN mock presentations

During the next RG (on Friday at 13:00) Kokos will give a mock presentation for CLIN and Meaghan will present her CLIN poster.

Does Logic-based Reasoning Work for Natural Language Inference in Dutch?
Lasha Abzianidze and Konstantinos Kogkalidis

Abstract: We compose a pair of syntactic parsers, in the form of Typelogical Grammar provers, with a Natural Logic Tableau theorem prover to create the first dedicated logic-based Natural Language Inference system for Dutch. The system predicts inferences based on the formal proofs that are completely transparent from an explanation point of view. Its evaluation on the recently translated Dutch Natural Language Inference dataset shows promising results for a logic-based system, remaining only within a 4% performance margin to a strong neural baseline. Additionally, during the training, the theorem prover learns lexical relations new to the Dutch WordNet. We also found aspects in which the Dutch dataset is more challenging than the original English one.

Generalised Minimalist Grammars
Meaghan Fowlie

Minimalist Grammars, Stabler’s (1997) formalisation of Chomsky’s (1995) Minimalist Program, are a mildly context sensitive grammar formalism. While Minimalist Grammars (MGs) have been in use for over two decades, with grammars generating strings, trees, and graphs, no unifying definition for MGs has yet been established: what qualifies these as MGs? What else could be an MG? What links their generative capacities?
To address these questions, I define Generalised Minimalist Grammars. I build on the “two-step” view of MGs, in which we consider separately the feature calculus, which determines which operations are defined when, and the algebra, which defines what those operations are and what they output. To define MGs in the general case, I describe constraints on the feature calculus and its mapping to what I call Generalised Minimalist Algebras (GMAs). I define GMAs to generalise the principles of Merge and Move, which are at the core of Minimalism, to arbitrary objects. In this way MGs can be defined to generate objects of any type, as long as they are built with an algebra that conforms to the definition of GMAs.

Results include:
1. A unifying definition for Minimalist Grammars, including a straightforward way to define synchronous MGs
2. For algebra objects with string yields, such as trees, a generalised MG is mildly context sensitive iff certain internal homomorphisms and its string yield function are linear and non-deleting.
3. Existing algebras from other formalisms can be used in MGAs to combine their insights. For instance, Dutch crossing dependencies are elegantly explained by Tree Adjoining Grammars; GMAs provide a simple way to combine TAGs with MGs, yielding a grammar that elegantly explains both crossing dependencies and Verb-Second phenomena.