Abstract:
We compute the real and complex Buchstaber numbers of an arbitrary Bier sphere. In dimension two, we identify all the 13 different combinatorial types of Bier spheres and show that 12 of them are nerve complexes of nestohedra, while the remaining one is merely nerve complex of generalized permutohedron. As an application of our results, we construct a regular normal fan for each of those 13 Delzant polytopes, compute cohomology rings of the corresponding nonsingular projective toric varieties and discuss orientability of the corresponding small covers.
I. Limonchenko was supported by the Ministry of Science, Innovations and Technological Development, Republic
of Serbia, through the Mathematical Institute of the Serbian Academy of Sciences and Arts. M. Sergeev was supported within the framework of the HSE University Basic Research Program.
Citation:
I. Yu. Limonchenko, M. A. Sergeev, “Bier spheres and toric topology”, Topology, Geometry, Combinatorics, and Mathematical Physics, Collected papers. Dedicated to Victor Matveevich Buchstaber on the occasion of his 80th birthday, Trudy Mat. Inst. Steklova, 326, Steklov Math. Inst., Moscow, 2024, 275–292