Natural language processing with functional parsers

Natural language Processing (NLP) can be done with a structural approach using grammar rules. (The other type of NLP is using statistical methods.) In this post I discuss the use of functional parsers for the parsing and interpretation of small sets of natural language sentences within specific contexts. Functional parsing is also known as monadic parsing and parsing combinators.

Generally, I am using functional parsers to make Domain-Specific Languages (DSL’s). I use DSL’s to make command interfaces to search and recommendation engines and also to design and prototype conversational engines. I use extensively the so called Backus-Naur Form (BNF) for the grammar specifications. Clearly a DSL can be very close to natural language and provide sufficient means for interpretation within a given (narrow) context. (Like function integration in Calculus, smart phone directory browsing and selection, or search for something to eat nearby.)

I implemented and uploaded a package for construction of functional parsers: see FunctionalParsers.m hosted by the project MathematicaForPrediction at GitHub.

The package provides ability to quickly program parsers using a core system of functional parsers as described in the article “Functional parsers” by Jeroen Fokker .

The parsers (in both the package and the article) are categorized in the groups: basic, combinators, and transformers. Immediate interpretation can be done with transformer parsers, but the package also provides functions for evaluation of parser output within a context of data and functions.

Probably most importantly, the package provides functions for automatic generation of parsers from grammars in EBNF.

Here is an example of parsing the sentences of an integration requests language:

Interpretation of integration requests

Here is the grammar:
Integration requests EBNF grammar

The grammar can be visualized with this mind map:

Integration command

The mind map was hand made with MindNode Pro. Generally, the branches represent alternatives, but if two branches are connected the direction of the arrow connecting them shows a sequence combination.

With the FunctionalParsers.m package we can automatically generate a
mind map parsing the string of the grammar in EBNF to OMPL:


(And here is a PDF of the automatically generated mind map: IntegrationRequestsGenerated . )

I also made a slide show that gives an introduction to how the package is used: “Functional parsers for an integration requests language grammar”.

A more complicated example is this conversational engine for manipulation of time series data. (Data loading, finding outliers and trends. More details in the next blog post.)