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Properties of Solution set of Tensor Complementarity Problem

Yisheng Song, Gaohang Yu

arXiv:1508.00069v3math.OC

TL;DR

The paper studies which structural tensor properties govern feasibility and boundedness in tensor complementarity problems. It characterizes these properties and proves global solution bounds for strictly semi-positive tensors, relating the bounds to Pareto eigenvalues in the symmetric case.

  • Problem

    The paper asks how the special structure of tensors shapes feasibility, boundedness, and other properties of the tensor complementarity problem.

    Source: §1 · pp. 2–3
  • Method

    The paper derives equivalences involving S- and R0-tensors and establishes upper bounds using eigenvalue-linked constants for symmetric tensors and a new quantity for nonsymmetric tensors.

    Source: §1 · p. 3, §5 · p. 12
  • Results

    A tensor is an S-tensor iff TCP(A,q) is feasible for every q, every Q-tensor is an S-tensor, and boundedness is equivalent to unique solvability at q=0.

    Source: §1 · p. 3, §3.1 · p. 7
  • Takeaways & Limitations

    For strictly semi-positive tensors, global solution upper bounds are proved; symmetric-tensor bounds closely relate to the smallest Pareto H-(Z-)eigenvalue, while nonsymmetric bounds use a new quantity.

    Source: §5 · p. 12

Abstract

from arXiv · show

The tensor complementarity problem is a specially structured nonlinear complementarity problem, then it has its particular and nice properties other than ones of the classical nonlinear complementarity problem. In this paper, it is proved that a tensor is an S-tensor if and only if the tensor complementarity problem is feasible, and each Q-tensor is an S-tensor. Furthermore, the boundedness of solution set of the tensor complementarity problem is equivalent to the uniqueness of solution for such a problem with zero vector. For the tensor complementarity problem with a strictly semi-positive tensor, we proved the global upper bounds for solution of such a problem. In particular, the upper bounds keep in close contact with the smallest Pareto $H-$($Z-$)eigenvalue.

1 Introduction

The introduction frames the tensor complementarity problem as a higher-order-tensor extension of classical complementarity that may have distinctive properties. It previews characterizations of feasibility and boundedness, along with global solution bounds for strictly semi-positive tensors.

1 Introduction

  • The introduction situates complementarity research in a broad application landscape and notes the established study of linear complementarity, including existence and uniqueness conditions.Applications listed for classical complementarity include optimization, economic equilibrium, mechanics, traffic equilibrium, and optimal control; linear complementarity results are attributed to Cottle, Pang and Stone and others.Source: §1 · p. 2
  • The tensor complementarity problem is presented as a natural extension of the linear complementarity problem with potentially distinctive properties arising from higher-order tensor structure.The introduction identifies studying those properties and their applications as the motivation for the paper.Source: §1 · p. 2
  • Prior tensor work studied solution existence for structured tensors, sparsest solutions for Z-tensor problems, and links between symmetric semi-positivity and copositivity.The cited examples include Song and Qi [13] [16] and Luo, Qi, Xiu [15].Source: §1 · p. 2
  • An S-tensor is equivalent to feasibility of the tensor complementarity problem for every q, every Q-tensor is an S-tensor, and boundedness is equivalent to unique solvability at zero.For strictly semi-positive tensors, the paper also establishes global solution upper bounds, linked to the smallest Pareto H-(Z-)eigenvalue.Source: §1 · pp. 2–3

2 Preliminaries

The preliminaries establish tensor and complementarity notation, collect tensor classes and solvability results, and introduce Pareto eigenvalues used in later bounds.

2 Preliminaries

  • A real tensor is a multi-array, and a symmetric tensor has entries invariant under permutations of its indices; tensor-vector operations also define a homogeneous polynomial of degree m.The preliminaries denote Ax^(m-1) as a vector and Ax^m as a degree-m homogeneous polynomial.Source: §2 · pp. 3–4
  • A Q-tensor makes TCP(A,q) solvable for every q, while an R0-tensor makes TCP(A,0) have a unique solution.The text also defines the feasible region and distinguishes feasibility from solvability.Source: §2 · p. 4
  • Every strictly semi-positive tensor is an R-tensor, every R-tensor is a Q-tensor, and a semi-positive R0-tensor is a Q-tensor.These implications are stated as Lemma 2.1, citing Song and Qi [13].Source: §2 · p. 5
  • Pareto H- and Z-eigenvalues are introduced to characterize copositivity, and the smallest Pareto Z-eigenvalue of a strictly copositive symmetric tensor is positive.The minimum is denoted μ(A) and satisfies μ(A) > 0.Source: §2 · pp. 5–6

3 Solution of the TCP(A, q)

The section characterizes feasibility through S-tensors and boundedness through R0-tensors, then establishes global solution bounds for strictly semi-positive tensors. It also relates bounded solution sets to the zero-vector problem and gives upper-bound results for symmetric cases.

3.1 S-tensor and feasible solution of the TCP(A, q)

  • A is an S-tensor if and only if TCP(A, q) is feasible for every q, and every Q-tensor is an S-tensor.Source: §3.1 · p. 7

3.2 R0-tensor and boundedness of solution set of the TCP (A, q)

  • A is an R0-tensor if and only if the stated Γ sets are bounded and the solution set of TCP(A, q) is bounded for every q.Source: §3.2 · p. 7
  • Strictly semi-positive tensors, and therefore P-tensors, have bounded TCP solution sets for every q.Source: §3.2 · p. 8

3.3 Solution of TCP(A, q) with strictly semi-positive tensors

  • For strictly semi-positive symmetric tensors, the section states global upper bounds for TCP solutions, including bounds involving quantities defined through eigenvalue results.Source: §3.3 · pp. 8–9
  • For symmetric tensors, strict semi-positivity is equivalent to strict copositivity, and q ≥ 0 yields the unique solution 0.Source: §3.3 · p. 9
  • The section introduces β(A) for strictly semi-positive tensors and states a further solution upper bound using this quantity.Source: §3.3 · p. 10
  • A strictly semi-positive tensor can induce a function that is not pseudo-monotone, while the corresponding complementarity problem has a solution.Source: §3.3 · pp. 10–11

4 Perspectives

The section identifies open questions about the scope and tightness of the paper’s global upper bounds for TCP solutions. It also asks whether a newly defined quantity for strictly semi-positive tensors has a global or local upper bound.

4 Perspectives

  • The paper leaves open whether the upper bounds for TCP solutions with strictly semi-positive symmetric tensors are the smallest possible.Source: §4 · p. 11
  • It asks whether strictly semi-positive tensors admit a positive lower bound for TCP solutions.Source: §4 · p. 11
  • The paper asks whether Z-, B-, H-, and M-tensors have similar global upper bounds for TCP solutions.Source: §4 · p. 11
  • For a strictly semi-positive tensor, it remains open whether the newly defined quantity β(A) has a global or local upper bound.Source: §4 · p. 11

5 Conclusions

The paper establishes equivalences between TCP feasibility and S-tensors, and between solution-set boundedness and R0-tensors. It also proves global upper bounds for TCP solutions with strictly semi-positive tensors, with distinct approaches for symmetric and nonsymmetric cases.

5 Conclusions

  • TCP feasibility is equivalent to being an S-tensor, while boundedness of the solution set is equivalent to being an R0-tensor.Source: §5 · p. 12
  • For strictly semi-positive symmetric tensors, global solution upper bounds are closely related to the smallest Pareto H-(Z-)eigenvalue.Source: §5 · p. 12
  • For strictly semi-positive nonsymmetric tensors, global solution upper bounds are proved using a newly introduced quantity.Source: §5 · p. 12
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