3 papers
math.DG2016
Singularities of tangent surfaces to directed curves
G. Ishikawa, T. Yamashita
A directed curve is a possibly singular curve with well-defined tangent lines along the curve. Then the tangent surface to a directed curve is naturally defined as the ruled surfac…
math.DG2016
Singularities of tangent surfaces to generic space curves
Goo Ishikawa, Tatsuya Yamashita
We give the complete solution to the local diffeomorphism classification problem of generic singularities which appear in tangent surfaces, in as wider situations as possible. We i…
math.AG2015
Leibniz complexity of Nash functions on differentiations
G. Ishikawa, T. Yamashita
The derivatives of Nash functions are Nash functions which are derived algebraically from their minimal polynomial equations. In this paper we show that, for any non-Nash analytic…