Let (B∗,β) be a chain bundle with algebraic Wu class v2k(β), and let ev denote evaluation on homology. Let Σ, Σ8, Λ, Coker, Q−, and ι1 be the constructions defined in the source. Conjecture on twisted groups. If (B∗,β) is (2k−1)-connected, then
L4k(B∗,β)≅W0(Qβ(2k))≅Σ(ev(v2k(β)))
and
Q4k(B∗,β)≅Σ8(ev(v2k(β))).
If (B∗,β) is (2k−2)-connected and ev(v2k(β))=0, then [vQβ(2k−1)′]=v2k(β) and
L4k−2(B∗,β)≅W0(Qβ(2k−1))≅Λ(vQβ(2k−1)′)
and
Q4k−2(B∗,β)≅Coker(Λ(ι1)→Λ(vQβ(2k−1)′)).
If instead (B∗,β) is (2k−2)-connected and ev(v2k(β))=0, then Qβ(2k−1)≅Q−⊕H2k−1(B∗) and
The conjecture is presented as a consequence of the preceding conjecture, the proposition computing quasi-Wu classes, and the theorem computing Witt groups; the source supplies no resolution.
References
Primary source
Diarmuid Crowley and Csaba Nagy, “The Witt groups of extended quadratic forms over Z”, arXiv:2404.09189 (2026).