ScalingStacks

4.2.3 Clemens polytopes and their contractions [03U6]

Original official author HTML, exact retained edition. Historical TeX conversion verdicts remain unchanged. Cited-edition alignment and mathematical self-containment are not assessed.

Complete original source context ยท Original author HTML

4.2.3 Clemens polytopes and their contractions

For any smooth projective variety XX of dimension nn, and and a snc model ๐’ณ{\cal X} of it (see Appendix A) we have a canonical projection to the corresponding Clemens polytope

p๐’ณ:Xaโ€‹nโ†’S๐’ณ.p_{{\cal X}}:X^{an}\rightarrow S_{{\cal X}}\,\,.

All interior points of nn-dimensional simplices of S๐’ณS_{{\cal X}} are p๐’ณp_{{\cal X}}-smooth, although there might be other smooth points too. More generally, one can compose projection p๐’ณp_{{\cal X}} with a continuous surjection ฯ€โ€ฒ:S๐’ณโ† B\pi^{\prime}:S_{{\cal X}}\twoheadrightarrow B where BB is a finite CW complex and map ฯ€โ€ฒ\pi^{\prime} is a cell map for some cell subdivision of S๐’ณS_{{\cal X}}. We assume that fibers of the composition ฯ€:=ฯ€โ€ฒโˆ˜p๐’ณ:Xaโ€‹nโ†’B\pi:=\pi^{\prime}\circ p_{{\cal X}}:X^{an}\to B are connected. This seems to be the most general case of maps from projective varieties over complete local fields to CW complexes relevant for our purposes.

Original mathematics by the credited authors. Source-backed reader collection; mathematical self-containment is not assessed.