Vector Symbolic Architectures for Context-Free Grammars

Vector symbolic architectures (VSA) are a viable approach for the hyperdimensional representation of symbolic data, such as documents, syntactic structures, or semantic frames. We present a rigorous mathematical framework for the representation of phrase structure trees and parse trees of context-free grammars (CFG) in Fock space, i.e. infinite-dimensional Hilbert space as being used in quantum field theory. We define a novel normal form for CFG by means of term algebras. Using a recently developed software toolbox, called FockBox, we construct Fock space representations for the trees built up by a CFG left-corner (LC) parser. We prove a universal representation theorem for CFG term algebras in Fock space and illustrate our findings through a low-dimensional principal component projection of the LC parser state. Our approach could leverage the development of VSA for explainable artificial intelligence (XAI) by means of hyperdimensional deep neural computation.

User-Defined Gestures with Physical Props in Virtual Reality

When interacting with virtual reality (VR) applications like CAD and open-world games, people may want to use gestures as a means of leveraging their knowledge from the physical world. However, people may prefer physical props over handheld controllers to input gestures in VR. We present an elicitation study where 21 participants chose from 95 props to perform manipulative gestures for 20 CAD-like and open-world game-like referents. When analyzing this data, we found existing methods for elicitation studies were insufficient to describe gestures with props, or to measure agreement with prop selection (i.e., agreement between sets of items). We proceeded by describing gestures as context-free grammars, capturing how different props were used in similar roles in a given gesture. We present gesture and prop agreement scores using a generalized agreement score that we developed to compare multiple selections rather than a single selection. We found that props were selected based on their resemblance to virtual objects and the actions they afforded; that gesture and prop agreement depended on the referent, with some referents leading to similar gesture choices, while others led to similar prop choices; and that a small set of carefully chosen props can support multiple gestures.

Introducing a Pure Weight-Based Concept for Automatic Test Case Generators

For decades, automatic test case generators for context-free grammars usually have adopted a derivation method designed to obtain the minimum set of shortest sentences.<div>Within this paper, a <i>pure weight-based</i> approach is described: such approach uniquely uses <i>weights </i>to select a rule while expanding a nonterminal symbol; we will assess how it is always possible to identify <i>balanced </i>weights which ensure the convergence of the process and we will see how the generated sentences are usually more complex than the shortest ones, so having more chances to exercise the underlying system more extensively.</div>

Stochastic Approach of Parsing Bengali Sentences

The parsing technique based on associate grammar rules as well as probability is called stochastic parsing. This paper suggested a probabilistic method to eliminate the uncertainty from the sentences of Bangla. The technique of Binarization is applied to increase the precision of the parsing. CYK algorithm is used in this paper. The work mainly focused on intonation-based sentences, for these reasons PCFGs (Probabilistic Context-Free Grammars) is based on proposed. About 30324 words are used to test the proposed system; average 93% accuracy is achieved. GUB JOURNAL OF SCIENCE AND ENGINEERING, Vol 7, Dec 2020 P 51-56

A New Semantics for Local Lexing

A revised semantics for Local Lexing is presented that entirely avoids priority conflicts between non-empty tokens. Pyramid Grammars are introduced, and their semantics is given in terms of Local Lexing. It is demonstrated that they are more expressive than context-free grammars, and at least as expressive as Parsing Expression Grammars.

RHYTHMIC SEMANTIC STRUCTURES “PARTICULARS AND UNIVERSALS” IN THE LYRICS OF ART SONGS AND ALGORYTHMS OF THEIR DETECTION

In order to study holistic cultural phenomena, including art songs, a tool reminiscent of LR(k)-parser of context-free grammars has been formalized. With the help of this algorithm a two-pass analysis of two works by different authors, united by the common theme of overcoming, was carried out. Two common structures were revealed in the texts: the semantic alternation of the "particulars and universals" oppositions (PU-rhythm) and the arrhythmic motif of overcoming (O-structure).