We study GL_2(F)-invariant periods on representations of GL_2(A), where F is a nonarchimedean local field and A/F product extensions total degree 3. For irreducible representations, theorem Prasad shows that the space such has dimension at most 1, non-zero when certain epsilon-factor condition holds. give an extension this result to class reducible (of Whittaker type), extending results Harris-...

A hereditary property R of graphs is said to be reducible if there exist hereditary properties P1,P2 such that G ∈ R if and only if the set of vertices of G can be partitioned into V (G) = V1 ∪ V2 so that 〈V1〉 ∈ P1 and 〈V2〉 ∈ P2. The problem of the factorization of reducible properties into irreducible factors is investigated.