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An algorithm for the factorization of split quaternion polynomials. (English) Zbl 1470.16051
Summary: We present an algorithm to compute all factorizations into linear factors of univariate polynomials over the split quaternions, provided such a factorization exists. Failure of the algorithm is equivalent to non-factorizability for which we present also geometric interpretations in terms of rulings on the quadric of non-invertible split quaternions. However, suitable real polynomial multiples of split quaternion polynomials can still be factorized and we describe how to find these real polynomials. Split quaternion polynomials describe rational motions in the hyperbolic plane. Factorization with linear factors corresponds to the decomposition of the rational motion into hyperbolic rotations. Since multiplication with a real polynomial does not change the motion, this decomposition is always possible. Some of our ideas can be transferred to the factorization theory of motion polynomials. These are polynomials over the dual quaternions with real norm polynomial and they describe rational motions in Euclidean kinematics. We transfer techniques developed for split quaternions to compute new factorizations of certain dual quaternion polynomials.
##### MSC:
 16S36 Ordinary and skew polynomial rings and semigroup rings 12D05 Polynomials in real and complex fields: factorization 51M09 Elementary problems in hyperbolic and elliptic geometries 51M10 Hyperbolic and elliptic geometries (general) and generalizations 70B10 Kinematics of a rigid body
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