The Sign Symmetric $P_{0,1}^{+}$-Matrix Completion Problem

We study sign symmetric $P_{0,1}^{+}$-matrix completion problem. It is shown that any non-asymmetric incomplete digraph lacks sign symmetric $P_{0,1}^{+}$-completion, digraphs of order at most four are completely classified and finally comparisons between sign symmetric $P_{0,1}^{+}$-completion and other matrix completions was given.