Michael Pinsker – Smooth approximations in oligomorphic clones
Vienna University of Technology
We present the novel method of smooth approximations which allows us
to extract information about an oligomorphic clone from an appropriate
subclone. This yields in turn a structural dichotomy for certain
oligomorphic clones: either they are equationally “simple", or there
is a witness of finite character for their non-simplicity. Applying
this to constraint satisfaction problems, we obtain complexity
classifications for various classes of omega-categorical structures.