An oriented variety $M$ without an orientation-reversing homeomorphism. Thus, for instance, the complex projective plane is an asymmetric variety, since the self-intersection of the complex straight line is $+1$ or $-1$, depending on the orientation. Certain knots can differ from their mirror image owing to the fact that their branched coverings are asymmetric varieties.
Comments
This notion can be found, e.g., in [Hi], Chapt. 5.
References
- [Hi] M.W. Hirsch, "Differential topology", Springer (1976) MR0448362 Zbl 0356.57001
Asymmetric variety. Encyclopedia of Mathematics. URL: http://encyclopediaofmath.org/index.php?title=Asymmetric_variety&oldid=53857