Some Results on Symmetric
نویسنده
چکیده
In this work, we investigate several natural computational problems related to identifying symmetric signings of symmetric matrices with specific spectral properties. We show NP-completeness for verifying whether an arbitrary matrix has a symmetric signing that is positive semi-definite, is singular, or has bounded eigenvalues. We exhibit a stark contrast between invertibility and the above-mentioned spectral properties by presenting a combinatorial characterization of matrices with invertible symmetric signings and an efficient algorithm using this characterization to verify whether a given matrix has an invertible symmetric signing. Finally, we give efficient algorithms to verify and find invertible and singular symmetric signing for matrices whose support graph is bipartite.
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