## Illinois Journal of Mathematics

### Calculus and invariants on almost complex manifolds, including projective and conformal geometry

#### Abstract

We construct a family of canonical connections and surrounding basic theory for almost complex manifolds that are equipped with an affine connection. This framework provides a uniform approach to treating a range of geometries. In particular, we are able to construct an invariant and efficient calculus for conformal almost Hermitian geometries, and also for almost complex structures that are equipped with a projective structure. In the latter case, we find a projectively invariant tensor the vanishing of which is necessary and sufficient for the existence of an almost complex connection compatible with the path structure. In both the conformal and projective setting, we give torsion characterisations of the canonical connections and introduce certain interesting higher order invariants.

#### Article information

Source
Illinois J. Math., Volume 57, Number 2 (2013), 383-427.

Dates
First available in Project Euclid: 19 August 2014

Permanent link to this document
https://projecteuclid.org/euclid.ijm/1408453588

Digital Object Identifier
doi:10.1215/ijm/1408453588

Mathematical Reviews number (MathSciNet)
MR3263039

Zentralblatt MATH identifier
1310.53024

#### Citation

Gover, A. Rod; Nurowski, Paweł. Calculus and invariants on almost complex manifolds, including projective and conformal geometry. Illinois J. Math. 57 (2013), no. 2, 383--427. doi:10.1215/ijm/1408453588. https://projecteuclid.org/euclid.ijm/1408453588

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