Hilbert's Theorem 90 and algebraic spaces
Stefan Schroeer
Abstract
In modern form, Hilbert's Theorem 90 tells us that R1f*(Gm)=0, where f is the canonical map between the etale site and the Zariski site of a scheme X. I construct examples showing that the corresponding statement for algebraic spaces does not hold. The first example is a nonseparated smooth 1-dimensional bug-eyed cover in Kollar's sense. The second example is a nonnormal proper algebraic space obtained by identifying points on suitable nonprojective smooth proper schemes.
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