On threefolds with the smallest nontrivial monodromy group

Abstract

. Using an adjunction-theoretic result due to A. J. Sommese together with a proposition from SGA7, we obtain a complete list of smooth threefolds for which the monodromy group acting on H 2 of its smooth hyperplane section is Z / 2 Z . The possibility of such a classification was announced by F. L. Zak in 1991.