Efficient Algorithms for Reconstruction of 2D-Arrays from Extended Parikh Images
TL;DR: The concept of a Parikh matrix or an extended Parikh mapping of words introduced by Mateescu et al (2001) is formulated here for two-dimensional (2D) arrays and the problem of reconstructing a 2D-array over {0,1} from its image under the extendedParikh mapping along three or more directions is shown to be NP-hard.
Abstract: The concept of a Parikh matrix or an extended Parikh mapping of words introduced by Mateescu et al (2001) is formulated here for two-dimensional (2D) arrays. A polynomial time algorithm is proposed to reconstruct an unknown 2D-array over { 0,1 } from its image under the extended Parikh mapping along a single direction. On the other hand the problem of reconstructing a 2D-array over { 0,1 } from its image under the extended Parikh mapping along three or more directions is shown to be NP-hard. Also a polynomial time algorithm to reconstruct a 2D-array over {0,1} with a maximum number of ones close to the main diagonal of the array is presented by reducing the problem to Min-cost Max-flow problem.
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Cites background from "Efficient Algorithms for Reconstruc..."
...Among a number of problems of interest related to digitized picture arrays (see for example [4, 9, 11]), investigation of combinatorial properties of arrays has been done (see for example [5, 6, 17])....
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...tion of binary images has been extensively studied (See for example [4, 11])....
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Cites methods from "Efficient Algorithms for Reconstruc..."
...,e problem of reconstruction of 2D binary images has been studied [22] based on Parikh matrices....
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References
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"Efficient Algorithms for Reconstruc..." refers background in this paper
...The extended Parikh mapping of words (also called Parikh matrix mapping) is defined in [ 1 ], wherein a particular triangular matrix is associated with each symbol in the alphabet....
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...Mateescu et al. [ 1 ] introduced an extension of the Parikh mapping of words, called extended Parikh mapping or Parikh matrix mapping of words which gives more information than the Parikh mapping....
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