II.1.15

This problems has Hartshorne Height 1.

HAPPY

 * The key to this problem is to reduce statements of morphisms of sheaves to statements about elements of sheaf groups.
 * Defining the sum of two morphisms is just defined pointwise on every open set as you would expect.
 * In particular, the zero and gluing sheaf axioms for Hom $$(F|_U,G|_U)$$ (here the underline means sheaf Hom) only require that G be a sheaf. For example, for the zero axiom, if a morphism restricts to 0 on some open cover means that the original morhpism maps elements to other elements that restricts to 0 in the groups of G, as G is a sheaf, the morphism must be mapping everything to 0.