Contraction groups in complete Kac-Moody groups

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Let G be an abstract Kac-Moody group over a finite field and G be the closure of the image of G in the automorphism group of its positive building. We show that if the Dynkin diagram associated to G is irreducible and neither of spherical nor of affine type, then the contraction groups of elements in G which are not topologically periodic are not closed. (In those groups there always exist elements which are not topologically periodic.)