ErgSemantics_Interface

Background

The Semantic Interface (SEM-I) is a specification of the ‘vocabulary’ and associated wellformedness constraints used in ERG meaning representations. In particular, the SEM-I inventorizes (a) the hierarchy of variable types; (b) the range of variable properties, associated value constraints, and appropriateness relative to variable types; and (c) the hierarchy of semantic predicates, each paired with its synopsis (‘argument frame’).

The notion of the SEM-I in the ERG continues a tradition of explicit interface specification (that can be interpreted independent of the core of the grammar) dating back to at least the Verbmobil project (in the 1990s of the past century). In DELPH-IN, this concept was further developed in the DeepThought and LOGON projects, among others, and some foundational reflections have been published by Flickinger et al. (2005). At about the same time, StephanOepen developed the software support (as part of the LKB environment) to largely automatically extract the semantic interface specification from the grammar sources. For the past ten or so years, each ERG release has provided an up-to-date SEM-I, but some sections were missing or incomplete until the ERG 1214 release (in mid-2016).

A High-Level Tour

As of the 1214 release, the ERG SEM-I is comprised of four files, viz. erg.smi, providing (a) and (b) from the above list, plus a few manually curated parts of (c); hierarchy.smi, setting up a partial (multi-rooted), multiple-inheritance hierarchy of semantic predicates; abstract.smi, listing the inventory of abstract predicates; and surface.smi, spelling out the (much larger) inventory of surface predicates. For the distinction between abstract vs. surface predicates, please see the ErgSemantics/Basics page.

variables:

  u.
  i < u.
  e < i : PERF bool, PROGR bool, MOOD bool, TENSE tense, SF sf.

properties:

 tense.
  tensed < tense.
  past < tensed.
  pres < tensed.
  fut < tensed.
  untensed < tense.

predicates:

  abstract_q : ARG0 x, BODY h, RSTR h.
  existential_q < abstract_q.
  universal_q < abstract_q.

‘Upward’ Extensions of the Predicate Hierarchy

Reflections on SEM-I Construction

When creating the files hierarchy.smi, abstract.smi, and surface.smi automatically from the grammar-internal type hierarchy, a set of heuristics is applied to decide which predicates to expose in the external interface. In the 1214 release, the set of abstract SEM-I predicates comprises some 120 entries, whereas there are some 500 abstract, non-glb types in the grammar-internal predicate hierarchy. In other words, the SEM-I is masking a large number of distinctions that the ERG makes internally (often for reasons of controlling syntactic combination and composition).