In 1993 Estes and Guralnick conjectured that any totally real
separable monic polynomial with rational integer coefficients
will occur as the minimal polynomial of some symmetric
matrix with rational integer entries. They proved this to be
true for all such polynomials that have degree at most 4.
In this paper, we show that for every d ≥ 6 there is a
polynomial of degree d that is a counterexample to this
conjecture. The only case still in doubt is degree 5.
One of the ingredients in the proof is to show that there are
Salem numbers of degree 2d and trace −2 for every d ≥ 12.
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