natural language processing Natural language processing (NLP) is an interdisciplinary subfield of linguistics, computer science, and artificial intelligence concerned with the interactions between computers and human language, in particular how to program computers to p ...
, semantic compression is a process of compacting a lexicon used to build a textual document (or a set of documents) by reducing language heterogeneity, while maintaining text semantics. As a result, the same ideas can be represented using a smaller set of words. In most applications, semantic compression is a lossy compression, that is, increased prolixity does not compensate for the lexical compression, and an original document cannot be reconstructed in a reverse process.

By generalization

Semantic compression is basically achieved in two steps, using frequency dictionaries and
semantic network A semantic network, or frame network is a knowledge base that represents semantic relations between concepts in a network. This is often used as a form of knowledge representation. It is a directed or undirected graph consisting of vertices, ...
: # determining cumulated term frequencies to identify target lexicon, # replacing less frequent terms with their hypernyms (
generalization A generalization is a form of abstraction whereby common properties of specific instances are formulated as general concepts or claims. Generalizations posit the existence of a domain or set of elements, as well as one or more common characteri ...
) from target lexicon. Step 1 requires assembling word frequencies and information on semantic relationships, specifically
hyponymy In linguistics, semantics, general semantics, and ontologies, hyponymy () is a semantic relation between a hyponym denoting a subtype and a hypernym or hyperonym (sometimes called umbrella term or blanket term) denoting a supertype. In other w ...
. Moving upwards in word hierarchy, a cumulative concept frequency is calculating by adding a sum of hyponyms' frequencies to frequency of their hypernym: cum f(k_) = f(k_) + \sum_ cum f(k_) where k_ is a hypernym of k_. Then, a desired number of words with top cumulated frequencies are chosen to build a targed lexicon. In the second step, compression mapping rules are defined for the remaining words, in order to handle every occurrence of a less frequent hyponym as its hypernym in output text. ;Example The below fragment of text has been processed by the semantic compression. Words in bold have been replaced by their hypernyms.
They are both nest building social insects, but paper wasps and honey bees organize their colonies in very different ways. In a new study, researchers report that despite their differences, these insects rely on the same network of genes to guide their social behavior.The study appears in the Proceedings of the Royal Society B: Biological Sciences. Honey bees and paper wasps are separated by more than 100 million years of evolution, and there are striking differences in how they divvy up the work of maintaining a colony.
The procedure outputs the following text:
They are both facility building insect, but insects and honey insects arrange their biological groups in very different structure. In a new study, researchers report that despite their difference of opinions, these insects act the same network of genes to steer their party demeanor. The study appears in the proceeding of the institution bacteria Biological Sciences. Honey insects and insect are separated by more than hundred million years of organic processes, and there are impinging differences of opinions in how they divvy up the work of affirming a biological group.

Implicit semantic compression

A natural tendency to keep natural language expressions concise can be perceived as a form of implicit semantic compression, by omitting unmeaningful words or redundant meaningful words (especially to avoid
pleonasm Pleonasm (; , ) is redundancy in linguistic expression, such as "black darkness" or "burning fire". It is a manifestation of tautology by traditional rhetorical criteria and might be considered a fault of style. Pleonasm may also be used for em ...

Applications and advantages

In the
vector space model Vector space model or term vector model is an algebraic model for representing text documents (and any objects, in general) as vectors of identifiers (such as index terms). It is used in information filtering, information retrieval, indexing and ...
, compacting a lexicon leads to a reduction of
dimensionality In physics and mathematics, the dimension of a mathematical space (or object) is informally defined as the minimum number of coordinates needed to specify any point within it. Thus, a line has a dimension of one (1D) because only one coordina ...
, which results in less
computational complexity In computer science, the computational complexity or simply complexity of an algorithm is the amount of resources required to run it. Particular focus is given to computation time (generally measured by the number of needed elementary operations) ...
and a positive influence on efficiency. Semantic compression is advantageous in
information retrieval Information retrieval (IR) in computing and information science is the process of obtaining information system resources that are relevant to an information need from a collection of those resources. Searches can be based on full-text or other co ...
tasks, improving their effectiveness (in terms of both precision and recall).{{cite book , first1=D. , last1=Ceglarek , first2=K. , last2=Haniewicz , first3=W. , last3=Rutkowski , chapter=Quality of semantic compression in classification , chapter-url=https://dl.acm.org/doi/10.5555/1947662.1947683 , title=Proceedings of the 2nd International Conference on Computational Collective Intelligence: Technologies and Applications , year=2010 , publisher=Springer , isbn=978-3-642-16692-1 , pages=162–171 , volume=1 This is due to more precise descriptors (reduced effect of language diversity – limited language redundancy, a step towards a controlled dictionary). As in the example above, it is possible to display the output as natural text (re-applying inflexion, adding stop words).

See also

Controlled natural language Controlled natural languages (CNLs) are subsets of natural languages that are obtained by restricting the grammar and vocabulary in order to reduce or eliminate ambiguity and complexity. Traditionally, controlled languages fall into two major type ...
Information theory Information theory is the scientific study of the quantification, storage, and communication of information. The field was originally established by the works of Harry Nyquist and Ralph Hartley, in the 1920s, and Claude Shannon in the 1940s. ...
* Lexical substitution * Quantities of information * Text simplification


External links

Semantic compression on Project SENECA (Semantic Networks and Categorization) website
Information retrieval techniques Natural language processing Quantitative linguistics Computational linguistics