ar X iv : m at h / 06 06 65 4 v 2 [ m at h . A T ] 1 6 O ct 2 00 6 EULER CHARACTERISTICS OF ALGEBRAIC VARIETIES

ar X iv : m at h / 06 06 65 4 v 3 [ m at h . A T ] 1 J ul 2 00 7 EULER CHARACTERISTICS OF ALGEBRAIC VARIETIES

This note studies the behavior of Euler characteristics and of intersection homology Euler characterstics under proper morphisms of algebraic (or analytic) varieties. The methods also yield, for algebraic (or analytic) varieties, formulae comparing these two kinds of Euler characteristics. The main results are direct consequences of the calculus of constructible functions and Grothendieck group...

ar X iv : m at h / 06 10 30 1 v 1 [ m at h . A G ] 9 O ct 2 00 6 ALGEBRAIC NAHM TRANSFORM FOR PARABOLIC HIGGS BUNDLES ON P

— In this paper, we give a completely algebraic description of Nahm transform for parabolic Higgs bundles on P. 2 KÜRŞAT AKER & SZILÁRD SZABÓ

ar X iv : m at h / 06 07 13 0 v 1 [ m at h . A G ] 5 J ul 2 00 6 TWISTED LOOP GROUPS AND THEIR AFFINE FLAG VARIETIES

ar X iv : m at h / 06 09 42 6 v 3 [ m at h . C O ] 1 5 O ct 2 00 6 SUM - PRODUCT ESTIMATES IN FINITE FIELDS VIA KLOOSTERMAN

We establish improved sum-product bounds in finite fields using incidence theorems based on bounds for classical Kloosterman and related sums.

ar X iv : m at h / 06 10 50 1 v 2 [ m at h . G T ] 1 8 O ct 2 00 6 INTRINSIC LINKING IS ARBITRARILY COMPLEX

We prove that given any n, λ ∈ N, there is a graph G which has the property that every embedding of G in R contains an ncomponent link all of whose components are pairwise linked with linking number greater than λ.