Spectra of weighted rooted graphs having prescribed subgraphs at some levels.
Let be a finite graph with an eigenvalue of multiplicity . A set of vertices in is called a star set for in if is not an eigenvalue of the star complement which is the subgraph of induced by vertices not in . A vertex subset of a graph is -regular if it induces a -regular subgraph and every vertex not in the subset has neighbors in it. We investigate the graphs having a -regular set which induces a star complement for some eigenvalue. A survey of known results is provided...
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