The THH homotopy-ring conjecture for truncated Brown–Peterson algebras

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For n≥0n\geq 0 and p>2p>2, let A∗=BP⁡⟨n⟩∗[x]/xeA_*=\operatorname{BP}\langle n\rangle_*[x]/x^e. Let wn+1,iw_{n+1,i}, yj,iy_{j,i}, and γpm(σ2xe)\gamma_{p^m}(\sigma^2x^e) denote the classes introduced in the preceding construction, with i≥0i\geq 0 and j≢p−1(modp)j\not\equiv p-1\pmod p. THH homotopy-ring conjecture. The ring spectrum THH⁡(BP⁡⟨n⟩[x]/xe/MU⁡[x])\operatorname{THH}(\operatorname{BP}\langle n\rangle[x]/x^e/\operatorname{MU}[x]) has homotopy ring

A∗[wn+1,i,yj,i:i≥0, j≢p−1(modp)]⊗A∗A∗[1/pm(σ2xe)pm:m≥0],A_*[w_{n+1,i},y_{j,i}:i\geq 0,\ j\not\equiv p-1\pmod p]\otimes_{A_*}A_*[1/p^m(\sigma^2x^e)^{p^m}:m\geq 0],

i.e. the ring map in the preceding remark is a surjection and its kernel is generated by {pmγ1(σ2xe)−γpm(σ2xe)}\{p^m\gamma_1(\sigma^2x^e)-\gamma_{p^m}(\sigma^2x^e)\}. The source states that this is true for n=0n=0; the conjecture concerns the remaining cases with n≥0n\geq 0 and p>2p>2.

References

Primary source

Rixin Fang, “Algebraic K-theory of finite algebras over higher local fields”, arXiv:2503.20383 (2026).

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