Singer's injectivity conjecture for the algebraic transfer

Let A\mathscr A be the Steenrod algebra over F2\mathbb F_2, and let Trq(F2)Tr_q(\mathbb F_2) denote the algebraic transfer in homology degree qq.

Singer's conjecture. The homomorphism

Trq(F2)Tr_q(\mathbb F_2)

is one-to-one for every qq.

Singer's conjecture concerns injectivity of the algebraic transfer, a map relating coinvariants in the cohomology of elementary abelian 2-groups to Ext\operatorname{Ext} over the Steenrod algebra. It is known in low homological degrees, including q=3q=3 and q=4q=4, but the paper states that it fails in bidegree (6,6+36)(6,6+36), so the conjecture is refuted.

Sources & referencesView supporting material

Primary source

Dang Vo Phuc, “Geometric realization via unoriented bordism and a counterexample to Singer's conjecture for the sixth algebraic transfer”, arXiv:2509.09455 (2026).

Additional references

14 papers in this index state this conjecture (2009–2025). The statement above is taken from the most recent of them; the others are arXiv:2506.10232, arXiv:2505.23218, arXiv:2412.02494, arXiv:2408.06669, arXiv:2408.15120, arXiv:2203.03703, arXiv:2106.10630, arXiv:2106.14605, arXiv:2106.14606, arXiv:2103.04393, arXiv:1609.02250, arXiv:1609.03006, and 1 more.

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