arXiv subjects

Takahisa Sasajima

Publications and source records attributed to Takahisa Sasajima.

2 recordsLinked to original sources

arXiv2017

Thom polynomials in $\mathcal{A}$-classification I: counting singular projections of a surface

We study universal polynomials of characteristic classes associated to the $\mathcal{A}$-classification (i.e. up to right-left equivalence) of holomorphic map-germs $(\mathbb{C}^2,0) \to (\mathbb{C}^n, 0)$ $(n=2,3)$. That enables us to systematically treat with classical enumerative problems of lines of prescribed contact with a given projective surface in $3$ and $4$-spaces.

math.AG↗

arXiv2017

Classical formulae on projective surfaces and $3$-folds with ordinary singularities, revisited

As an application of universal polynomials for local and multi-singularities of maps, we revisit classical enumerative formulae of Salmon-Cayley-Zeuthen for projective surfaces and analogous formulae of Segre-(B.)Severi-Roth for projective $3$-folds. In particular, several examples of actual computation are given using universal polynomials for computing weighted Euler characteristics of singularity loci.

math.AG↗