  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 field in positive characteristic. We also compute
the refined Swan conductor and the characteristic form of a character of the
fundamental group of a smooth separated scheme over a perfect field of positive
characteristic by using sheaves of Witt vectors.

Number Theory;Algebraic Geometry