Boone–Higman embeddings with higher finiteness. A finitely generated group has decidable word problem exactly when it embeds in a finitely presented simple group, proving the Boone–Higman conjecture. The target can have type F∞: a classifying space with finitely many cells in each dimension. A single group of type F∞ can also contain every finitely presented group.
released 2026-09-23 | 6 theorems · 16 lemmas · 21 proofs · 15,718 words |
PLAY LEVEL 1 »(pdf)
We prove the Boone–Higman conjecture. A finitely generated group has decidable word problem if and only if it embeds in a finitely presented simple group.
released 2026-09-23 | 6 theorems · 18 lemmas · 21 proofs · 13,826 words |
PLAY LEVEL 2 »(pdf)
Every finitely generated group with decidable word problem embeds in a simple group of type F∞. This resolves the higher-finiteness strengthening of the Boone–Higman conjecture.
released 2026-09-23 | 2 theorems · 6 lemmas · 11 proofs · 8,321 words |
PLAY LEVEL 3 »(pdf)
We construct a single group of type F∞ containing every finitely presented group. Its finitely generated subgroups, up to isomorphism, are exactly the finitely generated recursively presented groups. This answers the F∞ form of the higher-dimensional Higman embedding question.