Factor Analysis of Incidence Data via Novel Decomposition of Matrices

  • Authors:
  • Radim Belohlavek;Vilem Vychodil

  • Affiliations:
  • State University of New York at Binghamton, Binghamton, USA NY 13902---6000 and Palacky University, Olomouc, Olomouc, Czech Republic CZ-779 00;State University of New York at Binghamton, Binghamton, USA NY 13902---6000 and Palacky University, Olomouc, Olomouc, Czech Republic CZ-779 00

  • Venue:
  • ICFCA '09 Proceedings of the 7th International Conference on Formal Concept Analysis
  • Year:
  • 2009

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Abstract

Matrix decomposition methods provide representations of an object-variable data matrix by a product of two different matrices, one describing relationship between objects and hidden variables or factors, and the other describing relationship between the factors and the original variables. We present a novel approach to decomposition and factor analysis of matrices with incidence data. The matrix entries are grades to which objects represented by rows satisfy attributes represented by columns, e.g. grades to which an image is red or a person performs well in a test. We assume that the grades belong to a scale bounded by 0 and 1 which is equipped with certain aggregation operators and forms a complete residuated lattice. We present an approximation algorithm for the problem of decomposition of such matrices with grades into products of two matrices with grades with the number of factors as small as possible. Decomposition of binary matrices into Boolean products of binary matrices is a special case of this problem in which 0 and 1 are the only grades. Our algorithm is based on a geometric insight provided by a theorem identifying particular rectangular-shaped submatrices as optimal factors for the decompositions. These factors correspond to formal concepts of the input data and allow for an easy interpretation of the decomposition. We present the problem formulation, basic geometric insight, algorithm, illustrative example, experimental evaluation.