Cohomology of algebraic varieties and Galois representations

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I find that non-logarithmic version is geometrically more important than the logarithmic one in ramification theory. I constructed the non-logarithmic theory of the characteristic cycle of an l-adic sheaf in codimension at most 1. Using the method of cutting by curves and established acyclicity of morphisms of varieties.For a sheaf on a surface, I defined the characteristic cycle everywhere on the surface and proved a formula for the Euler number and an analog of the Milnor formula on vanishing cycles. Though limited to surfaces, this is a significant result achieving the aim to construct a theory of characteristic cycles in higher dimension.I also studied the determinant and the second Stiefel-Whitney class of the Galois representation defined by l-adic cohomology of a variety of even dimension.