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Published online by Cambridge University Press: 20 November 2018
Let   $J$  be an abelian variety and
 $J$  be an abelian variety and   $A$  be an abelian subvariety of
 $A$  be an abelian subvariety of   $J$  , both defined over
 $J$  , both defined over   $Q$ . Let
 $Q$ . Let   $x$  be an element of
 $x$  be an element of   ${{H}^{1}}\left( Q,\,A \right)$ . Then there are at least two definitions of
 ${{H}^{1}}\left( Q,\,A \right)$ . Then there are at least two definitions of   $x$  being visible in
 $x$  being visible in   $J$ : one asks that the torsor corresponding to
 $J$ : one asks that the torsor corresponding to   $x$  be isomorphic over
 $x$  be isomorphic over   $Q$  to a subvariety of
 $Q$  to a subvariety of   $J$ , and the other asks that
 $J$ , and the other asks that   $x$  be in the kernel of the natural map
 $x$  be in the kernel of the natural map   ${{H}^{1}}\left( Q,\,A \right)\,\to \,{{H}^{1}}\left( \text{Q},\,J \right)$ . In this article, we clarify the relation between the two definitions.
 ${{H}^{1}}\left( Q,\,A \right)\,\to \,{{H}^{1}}\left( \text{Q},\,J \right)$ . In this article, we clarify the relation between the two definitions.