geometry-topology / Stable homotopy theory: chromatic homotopy

Hopkins' chromatic splitting conjecture (weak and odd-prime strong forms)

Weak form: for the derived pp-completion X=Sp∧X=S_p^\wedge, the canonical map Ln−1X→Ln−1LK(n)XL_{n-1}X\to L_{n-1}L_{K(n)}X has no homotopy retraction at height n=pn=p for every p≥5p\ge5 and at n=p+1n=p+1 for every p≥7p\ge7; the class β1(p−1)2\beta_1^{(p-1)^2} is a nonzero kernel element (at p=5p=5, β116\beta_1^{16} in degree 608). Strong form: for p≥5p\ge5 the map L0LK(3)S→L0LK(2)LK(3)SL_0L_{K(3)}S\to L_0L_{K(2)}L_{K(3)}S is nonzero on π−3\pi_{-3}, so the height-three splitting fails even as an equivalence of E(2)E(2)-local spectra. Companions: at n=p=3n=p=3 the overlap is not in the thick subcategory generated by L0S,L1S,L2SL_0S,L_1S,L_2S; positively, for p>n+1p>n+1 the overlap has a 2n2^n-stage filtration with the predicted cofibers (nonsplit), with explicit attachments at height three. Heights below p−1p-1 remain open.

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geometry-topologySep 27, 2026Significance 40/100Registry: unreviewed

Hopkins' chromatic splitting conjecture (weak and odd-prime strong forms)

Prior state unknown→disproved

Weak form: for the derived pp-completion X=Sp∧X=S_p^\wedge, the canonical map Ln−1X→Ln−1LK(n)XL_{n-1}X\to L_{n-1}L_{K(n)}X has no homotopy retraction at height n=pn=p for every p≥5p\ge5 and at n=p+1n=p+1 for every p≥7p\ge7; the class β1(p−1)2\beta_1^{(p-1)^2} is a nonzero kernel element (at p=5p=5, β116\beta_1^{16} in degree 608). Strong form: for p≥5p\ge5 the map L0LK(3)S→L0LK(2)LK(3)SL_0L_{K(3)}S\to L_0L_{K(2)}L_{K(3)}S is nonzero on π−3\pi_{-3}, so the height-three…

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Weak form: for the derived pp-completion X=Sp∧X=S_p^\wedge, the canonical map Ln−1X→Ln−1LK(n)XL_{n-1}X\to L_{n-1}L_{K(n)}X has no homotopy retraction at height n=pn=p for every p≥5p\ge5 and at n=p+1n=p+1 for every p≥7p\ge7; the class β1(p−1)2\beta_1^{(p-1)^2} is a nonzero kernel element (at p=5p=5, β116\beta_1^{16} in degree 608). Strong form: for p≥5p\ge5 the map L0LK(3)S→L0LK(2)LK(3)SL_0L_{K(3)}S\to L_0L_{K(2)}L_{K(3)}S is nonzero on π−3\pi_{-3}, so the height-three splitting fails even as an equivalence of E(2)E(2)-local spectra. Companions: at n=p=3n=p=3 the overlap is not in the thick subcategory generated by L0S,L1S,L2SL_0S,L_1S,L_2S; positively, for p>n+1p>n+1 the overlap has a 2n2^n-stage filtration with the predicted cofibers (nonsplit), with explicit attachments at height three. Heights below p−1p-1 remain open.

Weak form: for the derived pp-completion X=Sp∧X=S_p^\wedge, the canonical map Ln−1X→Ln−1LK(n)XL_{n-1}X\to L_{n-1}L_{K(n)}X has no homotopy retraction at height n=pn=p for every p≥5p\ge5 and at n=p+1n=p+1 for every p≥7p\ge7; the class β1(p−1)2\beta_1^{(p-1)^2} is a nonzero kernel element (at p=5p=5, β116\beta_1^{16} in degree 608). Strong form: for p≥5p\ge5 the map L0LK(3)S→L0LK(2)LK(3)SL_0L_{K(3)}S\to L_0L_{K(2)}L_{K(3)}S is nonzero on π−3\pi_{-3}, so the height-three splitting fails even as an equivalence of E(2)E(2)-local spectra. Companions: at n=p=3n=p=3 the overlap is not in the thick subcategory generated by L0S,L1S,L2SL_0S,L_1S,L_2S; positively, for p>n+1p>n+1 the overlap has a 2n2^n-stage filtration with the predicted cofibers (nonsplit), with explicit attachments at height three. Heights below p−1p-1 remain open.

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