5 papers
Singular support and Characteristic cycle of a rank one sheaf in codimension two
Yuri Yatagawa
We compute the singular support and the characteristic cycle of a rank 1 sheaf on a smooth variety in codimension 2 using ramification theory, when the ramification of the sheaf is…
Characteristic cycle of a rank one sheaf and ramification theory
Yuri Yatagawa
We compute the characteristic cycle of a rank one sheaf on a smooth surface over a perfect field of positive characteristic. We construct a canonical lifting on the cotangent bundl…
Having the same wild ramification is preserved by the direct image
Yuri Yatagawa
We introduce the notion that two elements of Grothendieck groups of constructible sheaves on a separated scheme over an excellent henselian discrete valuation ring have the same wi…
Equality of two non-logarithmic ramification filtrations of abelianized Galois group in positive characteristic
Yuri Yatagawa
We prove the equality of two non-logarithmic ramification filtrations defined by Matsuda and Abbes-Saito for the abelianized absolute Galois group of a complete discrete valuation…
Wild ramification determines the characteristic cycle
Takeshi Saito, Yuri Yatagawa
Constructible complexes have the same characteristic cycle if they have the same wild ramification, even if the characteristics of the coefficients fields are different.