A reconstruction algorithm for a subclass of instances of the 2-color problem

  • Authors:
  • S. Brocchi;A. Frosini;S. Rinaldi

  • Affiliations:
  • Università di Firenze, Dipartimento di Sistemi e Informatica, viale Morgagni 65, 50134 Firenze, Italy;Università di Firenze, Dipartimento di Sistemi e Informatica, viale Morgagni 65, 50134 Firenze, Italy;Università di Siena, Dipartimento di Scienze Matematiche e Informatiche, Pian dei Mantellini 44, 53100 Siena, Italy

  • Venue:
  • Theoretical Computer Science
  • Year:
  • 2011

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Abstract

In the field of Discrete Tomography, the 2-color problem consists in reconstructing a matrix whose elements are of two different types, starting from its horizontal and vertical projections. It is known that the 1-color problem admits a polynomial time reconstruction algorithm, while the c-color problem, with c=2, is NP-hard. Thus, the 2-color problem constitutes an interesting example of a problem just in the frontier between hard and easy problems. In this paper we define a linear time algorithm (in the size of the output matrix) to solve a subclass of its instances, where some values of the horizontal and vertical projections are constant, while the others are upper bounded by a positive number proportional to the dimension of the problem. Our algorithm relies on classical studies for the solution of the 1-color problem.