Sample-Preserving Channel Retraction
Abstract
Fixed terminal observations admit an explicit output retraction without increasing the original canonical state budget.
Definition 1.1 (mapChannels).
Lean statement: D5/S0/Certificates/SkeletonChannelRetraction.mapChannels
Formalization. D5/S0/Certificates/SkeletonChannelRetraction.mapChannels (✓ std3).
Source. Repository-derived.
Commentary.
Postcompose the two terminal channels; retain the complete transition data.
Definition 1.2 (channelMap).
Lean statement: D5/S0/Certificates/SkeletonChannelRetraction.channelMap
Formalization. D5/S0/Certificates/SkeletonChannelRetraction.channelMap (✓ std3).
Source. Repository-derived.
Commentary.
Select the postcomposition associated with the original terminal channel.
Theorem 1.3 (evalFrom_mapChannels).
Lean statement: D5/S0/Certificates/SkeletonChannelRetraction.evalFrom_mapChannels
Proof. Machine-checked in Lean as D5/S0/Certificates/SkeletonChannelRetraction.evalFrom_mapChannels (✓ std3). ∎
Source. Repository-derived.
Commentary.
Exact evaluation commutes with channelwise postcomposition, including none.
Theorem 1.4 (eval_mapChannels).
Lean statement: D5/S0/Certificates/SkeletonChannelRetraction.eval_mapChannels
Proof. Machine-checked in Lean as D5/S0/Certificates/SkeletonChannelRetraction.eval_mapChannels (✓ std3). ∎
Source. Repository-derived.
Commentary.
Start-state version for the existing block-code input representation.
Definition 1.5 (signatureMap).
Lean statement: D5/S0/Certificates/SkeletonChannelRetraction.signatureMap
Formalization. D5/S0/Certificates/SkeletonChannelRetraction.signatureMap (✓ std3).
Source. Repository-derived.
Commentary.
Every old used signature maps to a used signature with the same return.
Theorem 1.6 (signatureMap_surjective).
Lean statement: D5/S0/Certificates/SkeletonChannelRetraction.signatureMap_surjective
Proof. Machine-checked in Lean as D5/S0/Certificates/SkeletonChannelRetraction.signatureMap_surjective (✓ std3). ∎
Source. Repository-derived.
Commentary.
Output retraction creates no signature outside the image of old ones.
Theorem 1.7 (canonical_state_card_mapChannels_le).
Lean statement: D5/S0/Certificates/SkeletonChannelRetraction.canonical_state_card_mapChannels_le
Proof. Machine-checked in Lean as D5/S0/Certificates/SkeletonChannelRetraction.canonical_state_card_mapChannels_le (✓ std3). ∎
Source. Repository-derived.
Commentary.
Canonical state cost cannot increase under either terminal retraction.
Theorem 1.8 (fixed_observation_preserved).
Lean statement: D5/S0/Certificates/SkeletonChannelRetraction.fixed_observation_preserved
Proof. Machine-checked in Lean as D5/S0/Certificates/SkeletonChannelRetraction.fixed_observation_preserved (✓ std3). ∎
Source. Repository-derived.
Commentary.
Fixed observed labels survive even when unobserved outputs change.
Definition 1.9 (recurrentRetract).
Lean statement: D5/S0/Certificates/SkeletonChannelRetraction.recurrentRetract
Formalization. D5/S0/Certificates/SkeletonChannelRetraction.recurrentRetract (✓ std3).
Source. Repository-derived.
Commentary.
In radix four, recurrent output two may be retracted to zero.
Definition 1.10 (transientRetract).
Lean statement: D5/S0/Certificates/SkeletonChannelRetraction.transientRetract
Formalization. D5/S0/Certificates/SkeletonChannelRetraction.transientRetract (✓ std3).
Source. Repository-derived.
Commentary.
In radix four, transient output zero may be retracted to one.
Theorem 1.11 (recurrentRetract_ne_two).
Lean statement: D5/S0/Certificates/SkeletonChannelRetraction.recurrentRetract_ne_two
Proof. Machine-checked in Lean as D5/S0/Certificates/SkeletonChannelRetraction.recurrentRetract_ne_two (✓ std3). ∎
Source. Repository-derived.
Commentary.
The recurrent retraction has precisely the intended forbidden-value exclusion.
Theorem 1.12 (transientRetract_ne_zero).
Lean statement: D5/S0/Certificates/SkeletonChannelRetraction.transientRetract_ne_zero
Proof. Machine-checked in Lean as D5/S0/Certificates/SkeletonChannelRetraction.transientRetract_ne_zero (✓ std3). ∎
Source. Repository-derived.
Commentary.
The transient retraction excludes zero without altering any other label.
Definition 1.13 (NormalRange).
Lean statement: D5/S0/Certificates/SkeletonChannelRetraction.NormalRange
Formalization. D5/S0/Certificates/SkeletonChannelRetraction.NormalRange (✓ std3).
Source. Repository-derived.
Commentary.
Finite-state candidates with the reduced terminal alphabets.
Theorem 1.14 (retracted_normalRange).
Lean statement: D5/S0/Certificates/SkeletonChannelRetraction.retracted_normalRange
Proof. Machine-checked in Lean as D5/S0/Certificates/SkeletonChannelRetraction.retracted_normalRange (✓ std3). ∎
Source. Repository-derived.
Commentary.
The explicit retraction constructs that range for every partial skeleton.
Theorem 1.15 (normalized_sample_feasibility_iff).
Lean statement: D5/S0/Certificates/SkeletonChannelRetraction.normalized_sample_feasibility_iff
Proof. Machine-checked in Lean as D5/S0/Certificates/SkeletonChannelRetraction.normalized_sample_feasibility_iff (✓ std3). ∎
Source. Repository-derived.
Commentary.
Reduced-output search is equisatisfiable at the same canonical budget. Only the given observations are assumed to avoid the two forbidden labels; the unknown original machine’s unobserved outputs are unrestricted.
References
- Truth anchor:
D5/S0/Certificates/SkeletonChannelRetraction.NormalRange - Truth anchor:
D5/S0/Certificates/SkeletonChannelRetraction.canonical_state_card_mapChannels_le - Truth anchor:
D5/S0/Certificates/SkeletonChannelRetraction.channelMap - Truth anchor:
D5/S0/Certificates/SkeletonChannelRetraction.evalFrom_mapChannels - Truth anchor:
D5/S0/Certificates/SkeletonChannelRetraction.eval_mapChannels - Truth anchor:
D5/S0/Certificates/SkeletonChannelRetraction.fixed_observation_preserved - Truth anchor:
D5/S0/Certificates/SkeletonChannelRetraction.mapChannels - Truth anchor:
D5/S0/Certificates/SkeletonChannelRetraction.normalized_sample_feasibility_iff - Truth anchor:
D5/S0/Certificates/SkeletonChannelRetraction.recurrentRetract - Truth anchor:
D5/S0/Certificates/SkeletonChannelRetraction.recurrentRetract_ne_two - Truth anchor:
D5/S0/Certificates/SkeletonChannelRetraction.retracted_normalRange - Truth anchor:
D5/S0/Certificates/SkeletonChannelRetraction.signatureMap - Truth anchor:
D5/S0/Certificates/SkeletonChannelRetraction.signatureMap_surjective - Truth anchor:
D5/S0/Certificates/SkeletonChannelRetraction.transientRetract - Truth anchor:
D5/S0/Certificates/SkeletonChannelRetraction.transientRetract_ne_zero - Dependency: D5/S0/Automata/BinaryZeckendorfBlockSkeleton