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refactor(MultiTape): keep the run path space API in Space.lean - #1145

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SamuelSchlesinger merged 1 commit into
leanprover:mainfrom
barni120400:refactor/multitape-space-api-home
Oct 20, 2026
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SamuelSchlesinger merged 1 commit into
leanprover:mainfrom
barni120400:refactor/multitape-space-api-home

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Moves the space API of run paths from TapeLemmas.lean to Space.lean, next to the space measures: the windows [-s, s], the bounds of a path's space by sets containing its head positions, and the space of a mapped path. prependOutputHom moves to Nondeterministic.lean.

Restates space_map_le so that the map carries each head to its tape at every configuration, and removes the unused space_le_of_subset, visitedByTapeHead_map and space_map_eq. Prepending output keeps every head in place, so transformsTapes_iff_nil_output reuses the space bound as it is.

Composed with Claude Code.

Comment thread Cslib/Computability/Machines/Turing/MultiTape/TapeLemmas.lean
Comment thread Cslib/Computability/Machines/Turing/MultiTape/Space.lean Outdated
Comment thread Cslib/Computability/Machines/Turing/MultiTape/Space.lean Outdated
The windows, the bounds of a path's space by sets containing its head
positions, and the space of a mapped path move from TapeLemmas.lean to
Space.lean, next to the space measures; `prependOutputHom` moves to
Nondeterministic.lean. Prepending output keeps every head in place, so
`transformsTapes_iff_nil_output` reuses the space bound as it is, and
the then unused `space_map_eq` goes.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
@barni120400
barni120400 force-pushed the refactor/multitape-space-api-home branch from 0aa2e4a to da022fb Compare October 19, 2026 21:40
@SamuelSchlesinger
SamuelSchlesinger added this pull request to the merge queue Oct 20, 2026
Merged via the queue into leanprover:main with commit b5f3b77 Oct 20, 2026
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2 participants