[geometry-ml:03568] 第12回応用特異点論ラボ・セミナーのお知らせ

[izumiya ＠ math.sci.hokudai.ac.jp]

幾何学メーリングリストの皆様

直前のお知らせですが、
第12回応用特異点論ラボ・セミナーのお知らせをお届けします。

応用特異点論ラボのウェッブページ 
https://sites.google.com/site/appliedsingularitytheorylab 

泉屋

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場所：　北海道大学、理学部3号館、210号室、

日時　12月13日（木）） 16:30--18:00

Speaker: Joachim Rieger (Martin Luther University Halle-Wittenberg)

Title: Projections of surfaces in P^3

Abstract:
For an open and dense set PG of real smooth surfaces M in real
projective 3-space P^3, the family of projections from points c in P^3
has C^0-versally unfolded multi-singularities belonging to a finite
list of equivalence classes (despite the appearance of certain
uni-modal multi-singularities in our classification).

The stratification of M by equisingularity classes of inner
projections (from points c of M) includes certain (most?) curves and
points of interest in the generic geometry of surfaces as strata, and
hence provides local models for the neighborhoods of such curves and
points in M.

A fairly complete picture of the enumerative geometry of complex
algebraic surfaces and their view bifurcation sets can be obtained for
a constructible set PGC (the complex analogue of PG) of "generic
degree of surfaces" from an old result of H. Schubert. In fact, H.
Schubert used the term "Allgemeine Ordnungsflache" (general degree of
surface) without defining it.