#### Document Type

Article

#### Publication Date

2009

#### Abstract

Let *H* be an *m *x* n* real matrix and let Z_{i} be the set of column indices of the zero entries of row* i* of *H*. Then the conditions |*Z _{k}* ∩(U

^{k-1}

_{i=1}

*Z*)| ≤ 1 for all

_{i}*k*(2 ≤

*k*≤

*m*) are called the (row) Zero Position Conditions (ZPCs). If

*H*satisfies the ZPC, then

*H*is said to be a (row) ZPC matrix. If

*H*satisfies the ZPC, then

^{T}*H*is said to be a column ZPC matrix. The real matrix

*H*is said to have a zero cycle if

*H*has a sequence of at least four zero entries of the form

*h*in which the consecutive entries alternatively share the same row or column index (but not both), and the last entry has one common index with the first entry. Several connections between the ZPC and the nonexistence of zero cycles are established. In particular, it is proved that a matrix

_{i1j1}, h_{i1j2}, h_{i2j2}, h_{i2j3}, ...,h_{ikjk}, h_{ikj1}*H*has no zero cycle if and only if there are permutation matrices

*P*and

*Q*such that

*PHQ*is a row ZPC matrix and a column ZPC matrix.

#### Recommended Citation

Arav, M., Hall, F., Li, Z., & Rao, B. (2009). ZPC matrices and zero cycles. *International Journal of Combinatorics*, Article ID 520923, 1-5. doi:10.1155/2009/520923

#### Creative Commons License

This work is licensed under a Creative Commons Attribution 3.0 License.

## Comments

This article was originally published in the

International Journal of Combinatorics.It is reposted here with the permission of the authors. Copyright © 2009 Marina Arav, et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.