4. VECTOR SPACE MODEL (VSM)
Vector Space Model (VSM) is an algebraic model used for information filtering, information retrieval, indexing and relevance ranking [2]. The Vector Space Model is a way of representing and comparing documents and queries based on words (keywords) with values [2]. This model can be used to rank the similarity between documents – not just to answer if document contains required words or not. Each component of a vector represents one term/keyword, and has a value. The value is a real number that indicates how relevant a term is to the document or query being described [2]. VSM processing can be divided into two stages: Document Indexing with Term Weighting and Documents Relevancy Ranking.