# zbMATH — the first resource for mathematics

Integrability of almost quaternal structures. (English) Zbl 0573.53021
The author is studying further almost quaternal structures introduced in a previous paper [ibid. 23, 287-298 (1977; Zbl 0373.53017)]. First, he proves that the set of torsion-free adapted connections is obtained by Q- projective transformations only, provided the torsion invariant of the almost quaternal structure is trivial. Then he shows that the almost quaternal structure is integrable if and only if the Chern-Bernard and curvature invariants are trivial.
Reviewer: A.Bejancu

##### MSC:
 53C10 $$G$$-structures 53C15 General geometric structures on manifolds (almost complex, almost product structures, etc.)