scholarly journals Contralog: a Prolog conform forward-chaining environment and its application for dynamic programming and natural language parsing

2016 ◽  
Vol 8 (1) ◽  
pp. 41-62
Author(s):  
Imre Kilián
Keyword(s):  
Dynamic Programming ◽  
Natural Language ◽  
Inference Engine ◽  
Recursive Definition ◽  
Target Model ◽  
Forward Chaining ◽  
Natural Language Parsing ◽  
Multiplication Problem ◽  
Inference Strategy ◽  
Definition Of

Abstract The backward-chaining inference strategy of Prolog is inefficient for a number of problems. The article proposes Contralog: a Prolog-conform, forward-chaining language and an inference engine that is implemented as a preprocessor-compiler to Prolog. The target model is Prolog, which ensures mutual switching from Contralog to Prolog and back. The Contralog compiler is implemented using Prolog's de facto standardized macro expansion capability. The article goes into details regarding the target model. We introduce first a simple application example for Contralog. Then the next section shows how a recursive definition of some problems is executed by their Contralog definition automatically in a dynamic programming way. Two examples, the well-known matrix chain multiplication problem and the Warshall algorithm are shown here. After this, the inferential target model of Prolog/Contralog programs is introduced, and the possibility for implementing the ReALIS natural language parsing technology is described relying heavily on Contralog's forward chaining inference engine. Finally the article also discusses some practical questions of Contralog program development.

scholarly journals Splittability of Bilexical Context-Free Grammars is Undecidable

2011 ◽  
Vol 37 (4) ◽  
pp. 867-879
Author(s):  
Mark-Jan Nederhof ◽  
Giorgio Satta
Keyword(s):  
Dynamic Programming ◽  
Natural Language ◽  
Input String ◽  
Running Time ◽  
Natural Language Parsing ◽  
Central Interest ◽  
The Right ◽  
Programming Algorithms ◽  
Context Free ◽  
Context Free Grammars

Bilexical context-free grammars (2-LCFGs) have proved to be accurate models for statistical natural language parsing. Existing dynamic programming algorithms used to parse sentences under these models have running time of O(∣w∣4), where w is the input string. A 2-LCFG is splittable if the left arguments of a lexical head are always independent of the right arguments, and vice versa. When a 2-LCFGs is splittable, parsing time can be asymptotically improved to O(∣w∣3). Testing this property is therefore of central interest to parsing efficiency. In this article, however, we show the negative result that splittability of 2-LCFGs is undecidable.

CoreALMlib: An library translated from the Component Library

2016 ◽  
Vol 16 (5-6) ◽  
pp. 800-816 ◽  
Author(s):  
DANIELA INCLEZAN
Keyword(s):  
Natural Language ◽  
Answer Set Programming ◽  
Natural Language Understanding ◽  
Inference Engine ◽  
Lexical Resources ◽  
Language Understanding ◽  
Commonsense Knowledge ◽  
Component Library ◽  
Action Language ◽  
Answer Set

AbstractThis paper presents CoreALMlib, an $\mathscr{ALM}$ library of commonsense knowledge about dynamic domains. The library was obtained by translating part of the Component Library (CLib) into the modular action language $\mathscr{ALM}$. CLib consists of general reusable and composable commonsense concepts, selected based on a thorough study of ontological and lexical resources. Our translation targets CLibstates (i.e., fluents) and actions. The resulting $\mathscr{ALM}$ library contains the descriptions of 123 action classes grouped into 43 reusable modules that are organized into a hierarchy. It is made available online and of interest to researchers in the action language, answer-set programming, and natural language understanding communities. We believe that our translation has two main advantages over its CLib counterpart: (i) it specifies axioms about actions in a more elaboration tolerant and readable way, and (ii) it can be seamlessly integrated with ASP reasoning algorithms (e.g., for planning and postdiction). In contrast, axioms are described in CLib using STRIPS-like operators, and CLib's inference engine cannot handle planning nor postdiction.

Parsing

2017 ◽  
Author(s):  
John Carroll
Keyword(s):  
Natural Language ◽  
Dependency Parsing ◽  
Grammatical Structure ◽  
Linguistic Information ◽  
Natural Language Parsing ◽  
Feature Structures ◽  
Key Concepts ◽  
Learning From Text ◽  
Dependency Structures ◽  
Context Free

This chapter introduces key concepts and techniques for natural-language parsing: that is, finding the grammatical structure of sentences. The chapter introduces the fundamental algorithms for parsing with context-free (CF) phrase structure grammars, how these deal with ambiguous grammars, and how CF grammars and associated disambiguation models can be derived from syntactically annotated text. It goes on to consider dependency analysis, and outlines the main approaches to dependency parsing based both on manually written grammars and on learning from text annotated with dependency structures. It finishes with an overview of techniques used for parsing with grammars that use feature structures to encode linguistic information.

scholarly journals Optimal Decision Trees on Simplicial Complexes

10.37236/1900 ◽  
2005 ◽  
Vol 12 (1) ◽  
Author(s):  
Jakob Jonsson
Keyword(s):  
Decision Tree ◽  
Decision Trees ◽  
Simplicial Complex ◽  
Elementary Theory ◽  
Simplicial Complexes ◽  
Optimal Decision ◽  
Property A ◽  
Recursive Definition ◽  
Topological Combinatorics ◽  
Definition Of

We consider topological aspects of decision trees on simplicial complexes, concentrating on how to use decision trees as a tool in topological combinatorics. By Robin Forman's discrete Morse theory, the number of evasive faces of a given dimension $i$ with respect to a decision tree on a simplicial complex is greater than or equal to the $i$th reduced Betti number (over any field) of the complex. Under certain favorable circumstances, a simplicial complex admits an "optimal" decision tree such that equality holds for each $i$; we may hence read off the homology directly from the tree. We provide a recursive definition of the class of semi-nonevasive simplicial complexes with this property. A certain generalization turns out to yield the class of semi-collapsible simplicial complexes that admit an optimal discrete Morse function in the analogous sense. In addition, we develop some elementary theory about semi-nonevasive and semi-collapsible complexes. Finally, we provide explicit optimal decision trees for several well-known simplicial complexes.

scholarly journals Modified Bar Recursion

2002 ◽  
Vol 9 (14) ◽  
Author(s):  
Ulrich Berger ◽  
Paulo B. Oliva
Keyword(s):  
Classical Analysis ◽  
Recursive Definition ◽  
Definition Of ◽  
Axiom Of Countable Choice

We introduce a variant of Spector's bar recursion (called "modified bar recursion'') in finite types to give a realizability interpretation of the classical axiom of countable choice allowing for the extraction of witnesses from proofs of Sigma_1 formulas in classical analysis. As a second application of modified bar recursion we present a bar recursive definition of the fan functional. Moreover, we show that modified bar recursion exists in M (the model of strongly majorizable functionals) and is not S1-S9 computable in C (the model of total functionals). Finally, we show that modified bar recursion defines Spector's bar recursion primitive recursively.

Migrating from ISO/IEC 9126 to SQUARE

2017 ◽  
pp. 160-178
Author(s):  
Paula Estrella ◽  
Nikos Tsourakis
Keyword(s):  
Natural Language ◽  
Potential User ◽  
Use Case ◽  
Relative Importance ◽  
Quality Model ◽  
Evaluation Methodologies ◽  
Model Based ◽  
Fair Comparison ◽  
Definition Of ◽  
Current Standards

When it comes to the evaluation of natural language systems, it is well acknowledged that there is a lack of common evaluation methodologies, making the fair comparison of such systems a difficult task. Many attempts to standardize this process have used a quality model based on the ISO/IEC 9126 standards. The authors have also used these standards for the definition of a weighted quality model for the evaluation of a medical speech translator, showing the relative importance of the system's features depending on the potential user (patient or doctor, developer). More recently, ISO/IEC 9126 has been replaced by a new series of standards, the 25000 or SQuaRE series, indicating that the model should be migrated to the new series in order to maintain compliance adherence to current standards. This chapter demonstrates how to migrate from ISO/IEC 9126 to ISO 25000 by using the authors' previous work as a use case.

Sign in / Sign up

Export Citation Format

Share Document