Homology and finiteness properties of SL₂(ℤ[t,t⁻¹])

Infinite-dimensional cohomology of SL2(Z[t,

“…Bux-Wortman also ask whether their proof can be extended to show the stronger result that H 2 (SL 2 (Z[t, t −1 ]); Z) is infinitely generated. Knudson proves that this is the case in [Knu08] using algebraic methods. Note that this result also follows from Theorem 1: Since Q is a field, H 2 (SL 2 (Z[t, t −1 ]); Q) ≃ Hom(H 2 (SL 2 (Z[t, t −1 ]); Q), Q)…”