Decomposition of integer matrices and multileaf collimator sequencing

Davaatseren Baatar, Horst W. Hamacher, Matthias Ehrgott, Gerhard J. Woeginger

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In this paper, we consider the problem of decomposing an integer matrix into a weighted sum of binary matrices that have the strict consecutive ones property. This problem is motivated by an application in cancer radiotherapy planning, namely the sequencing of multileaf collimators to realize a given intensity matrix. In addition, we also mention another application in the design of public transportation. We are interested in two versions of the problem, minimizing the sum of the coefficients in the decomposition (decomposition time) and minimizing the number of matrices used in the decomposition (decomposition cardinality). We present polynomial time algorithms for unconstrained and constrained versions of the decomposition time problem and prove that the (unconstrained) decomposition cardinality problem is strongly NP-hard. For the decomposition cardinality problem, some polynomially solvable special cases are considered and heuristics are proposed for the general case.

Original languageEnglish
Pages (from-to)6-34
Number of pages29
JournalDiscrete Applied Mathematics
Issue number1-3
Publication statusPublished - 1 Nov 2005
Externally publishedYes


  • Consecutive ones property
  • Decomposition of integer matrices
  • Multileaf collimator sequencing
  • Radiotherapy

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