Graphs with Multiple Sources per Vertex

TL;DR

This paper introduces a modification to the AM-algebra for Abstract Meaning Representations, allowing vertices with multiple sources to better handle reflexive sentences in natural language processing.

Contribution

It proposes a new definition of s-graphs with multiple sources per vertex and adapts the algebra's type system to support this extension.

Findings

Enables parsing of reflexive sentences like "The raven washes herself".

Maintains linguistic plausibility while extending the algebra's capabilities.

Provides a formal framework for graphs with multiple sources per vertex.

Abstract

Several attempts have been made at constructing Abstract Meaning Representations (AMRs) compositionally, and recently the idea of using s-graphs with the HR-algebra (Koller, 2015) has been simplified to reduce the number of options when parsing (Groschwitz et al., 2017). This apply-modify algebra (AM-algebra) is a linguistically plausible graph algebra with two classes of operations, both of rank two: the apply operation is used to combine a predicate with its argument; the modify operation is used to modify a predicate. While the AM-algebra correctly handles relative clauses and complex cases of coordination, it cannot parse reflexive sentences like: "The raven washes herself." To facilitate processing of such reflexive sentences, this paper proposes to change the definition of s-graphs underlying the AM-algebra to allow vertices with multiple sources, and additionally proposes an adaption to the type system of the algebra to correctly handle such vertices.