Research proof index

Given any short exact sewuence 0 → A → B → C → 0 in Rep R G and any subgroup H of G, the following diagram is commutative Hⁿ(G,C) ⟶ H^{n+1}(G A) | | ↓ ↓ Hⁿ(H,C) ⟶ H^{n+1}(G A). The vertical arrows are restriction and the horizontals are connecting homomorphisms. For this, it would be sensible to define restriction as a natural transformation, so t...