Complete solution of tropical vector inequalities using matrix sparsification

Research output: Contribution to conferenceAbstractpeer-review


We consider linear vector inequalities defined in the framework of a linearly ordered tropical semifield (a semiring with idempotent addition and invertible multiplication). The problem is to solve two-sided inequalities, which have an unknown vector included in both sides, each taking the form of a given matrix multiplied by this unknown vector. Observing that the set of solutions is closed under vector addition and scalar multiplication, we reduce the problem to finding a matrix whose columns generate the entire solution set.
We represent the solution as a family of subsets, each defined by a matrix that is obtained from the given matrices by using a matrix sparsification technique. The technique exploits sparsified matrices to derive a series of new inequalities, which admit a direct solution in the form of matrices that generate their solutions. We describe a
backtracking procedure that reduces the brute-force search of sparsified matrices by skipping those, which cannot provide solutions, and thus offers an economical way to obtain all subsets in the family. The columns in the generating matrices for subsets are combined together to form a matrix, which is further reduced to have only columns that constitute a minimal generating system of the solution. We use the reduced matrix to represent a complete exact solution of the two-sided inequality under consideration in a compact vector form.
We illustrate the results with numerical examples. Extension of the approach to solve two-sided equations is also discussed.
Original languageEnglish
StatePublished - 2019
EventInternational Conference on Matrix Analysis and its Applications - Liblice, Czech Republic
Duration: 8 Sep 201913 Sep 2019
Conference number: 8


ConferenceInternational Conference on Matrix Analysis and its Applications
Abbreviated titleMAT TRIAD 2019
Country/TerritoryCzech Republic
Internet address

Scopus subject areas

  • Algebra and Number Theory


  • tropical semifield
  • linear inequality
  • matrix sparsification
  • complete solution
  • backtracking


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