Families of Pisot numbers with negative trace
We give a complete classification of all pairs of cyclotomic polynomials whose zeros interlace on the unit circle, making explicit a result essentially contained in work of Beukers and Heckman. We show that each such pair corresponds to a single polynomial from a certain special class of integer polynomials, the 2-reciprocal discbionic polynomials. We also show that each such pair also corresponds (in four different ways) to a single Pisot polynomial from a certain restricted class, the cyclogenic...
Let be an elliptic curve defined over , the finite field of elements. We show that for some constant depending only on , there are infinitely many positive integers such that the exponent of , the group of -rational points on , is at most . This is an analogue of a result of R. Schoof on the exponent of the group of -rational points, when a fixed elliptic curve is defined over and the prime tends to infinity.
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