Morphological Cues for Lexical Semantics

Most natural language processing tasks require lexical semantic information. Automated acquisition of this information would thus increase the robustness and portability of NLP systems. This paper describes an acquisition method which makes use of fixed correspondences between derivational affixes and lexical semantic information. One advantage of this method, and of other methods that rely only on surface characteristics of language, is that the necessary input is currently available

Changing a semantics: opportunism or courage?

The generalized models for higher-order logics introduced by Leon Henkin, and their multiple offspring over the years, have become a standard tool in many areas of logic. Even so, discussion has persisted about their technical status, and perhaps even their conceptual legitimacy. This paper gives a systematic view of generalized model techniques, discusses what they mean in mathematical and philosophical terms, and presents a few technical themes and results about their role in algebraic representation, calibrating provability, lowering complexity, understanding fixed-point logics, and achieving set-theoretic absoluteness. We also show how thinking about Henkin's approach to semantics of logical systems in this generality can yield new results, dispelling the impression of adhocness. This paper is dedicated to Leon Henkin, a deep logician who has changed the way we all work, while also being an always open, modest, and encouraging colleague and friend.Comment: 27 pages. To appear in: The life and work of Leon Henkin: Essays on his contributions (Studies in Universal Logic) eds: Manzano, M., Sain, I. and Alonso, E., 201

Lexical information from a minimalist point of view

Simplicity as a methodological orientation applies to linguistic theory just as to any other field of research: ‘Occam’s razor’ is the label for the basic heuristic maxim according to which an adequate analysis must ultimately be reduced to indispensible specifications. In this sense, conceptual economy has been a strict and stimulating guideline in the development of Generative Grammar from the very beginning. Halle’s (1959) argument discarding the level of taxonomic phonemics in order to unify two otherwise separate phonological processes is an early characteristic example; a more general notion is that of an evaluation metric introduced in Chomsky (1957, 1975), which relates the relative simplicity of alternative linguistic descriptions systematically to the quest for explanatory adequacy of the theory underlying the descriptions to be evaluated. Further proposals along these lines include the theory of markedness developed in Chomsky and Halle (1968), Kean (1975, 1981), and others, the notion of underspecification proposed e.g. in Archangeli (1984), Farkas (1990), the concept of default values and related notions. An important step promoting this general orientation was the idea of Principles and Parameters developed in Chomsky (1981, 1986), which reduced the notion of language particular rule systems to universal principles, subject merely to parametrization with restricted options, largely related to properties of particular lexical items. On this account, the notion of a simplicity metric is to be dispensed with, as competing analyses of relevant data are now supposed to be essentially excluded by the restrictive system of principles

Distributive Laws for Monotone Specifications

Turi and Plotkin introduced an elegant approach to structural operational semantics based on universal coalgebra, parametric in the type of syntax and the type of behaviour. Their framework includes abstract GSOS, a categorical generalisation of the classical GSOS rule format, as well as its categorical dual, coGSOS. Both formats are well behaved, in the sense that each specification has a unique model on which behavioural equivalence is a congruence. Unfortunately, the combination of the two formats does not feature these desirable properties. We show that monotone specifications - that disallow negative premises - do induce a canonical distributive law of a monad over a comonad, and therefore a unique, compositional interpretation.Comment: In Proceedings EXPRESS/SOS 2017, arXiv:1709.0004

Mendler-style Iso-(Co)inductive predicates: a strongly normalizing approach

We present an extension of the second-order logic AF2 with iso-style inductive and coinductive definitions specifically designed to extract programs from proofs a la Krivine-Parigot by means of primitive (co)recursion principles. Our logic includes primitive constructors of least and greatest fixed points of predicate transformers, but contrary to the common approach, we do not restrict ourselves to positive operators to ensure monotonicity, instead we use the Mendler-style, motivated here by the concept of monotonization of an arbitrary operator on a complete lattice. We prove an adequacy theorem with respect to a realizability semantics based on saturated sets and saturated-valued functions and as a consequence we obtain the strong normalization property for the proof-term reduction, an important feature which is absent in previous related work.Comment: In Proceedings LSFA 2011, arXiv:1203.542