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A ’missing’ family of classical orthogonal polynomials. (English) Zbl 1222.33011

The authors introduce a missing family of orthogonal polynomials through limit of little \(q\)-Jacobi polynomials when \(q\) goes to \(-1\). The polynomials thus obtained are indeed classical and satisfy a three-term recurrence relation (which is a general feature of polynomials) and an eigenvalue equation with a differential operator of Dunkl type. Originally, the concept of orthogonal polynomials for \(q=-1\) was introduced by {R. A. Askey} and {M. E. H. Ismile} [Mem. Am. Math. Soc. 300, 108 p. (1984; Zbl 0548.33001)] for the \(q\)-ultraspherical polynomials. The authors also show that, these polynomials provide a nontrivial realization of the Askey-Wilson algebra for \(q=-1\) and they reduce to the ordinary Jacobi polynomials under certain specific conditions.

MSC:

33C45 Orthogonal polynomials and functions of hypergeometric type (Jacobi, Laguerre, Hermite, Askey scheme, etc.)
33C47 Other special orthogonal polynomials and functions
42C05 Orthogonal functions and polynomials, general theory of nontrigonometric harmonic analysis

Citations:

Zbl 0548.33001