The frame across a separated two-path step #
The separated transport keeps isOut verbatim, so the chain
direction observable is preserved pointwise; canonicality after
the step is therefore measured by the new chords' low ends
against the old directions — pure label combinatorics. The new
pairing's rigidity forces the re-paired ends to carry opposite
directions, a constraint on the old frame derived from the new
system.
The separated transport preserves the chain direction at every flag.
The re-paired ends carry opposite directions: the new chord's rigidity, read back through the preserved directions, is a constraint on the old frame.
Membership in the transported frame's anti-canonical set: directions are the old ones, labels are the new chords'.
Untouched chains keep their anti-canonicality across the transported step: off the four re-paired ends both the label comparison and the direction are unchanged.
The canonical direction formula: on a participating chain a
canonical frame points true exactly at the high-labelled end.
The four-end evaluation: from a canonical frame, an end of
a re-paired chord is anti-canonical after the transported step
exactly when it is low in its new chord but was high in its old
one. (Instantiate at the four swap ends with the new partners
from pathMatch_repair_swap.)
The transported anti-canonical set lives on the four re-paired ends: from a canonical source frame, every other chain stays canonical.
The low end of the (e₁, e₂) chord, as a flag.
Equations
- F.newLow he₁ e₂ he₂ = if F.boundaryLabel he₁ < F.boundaryLabel he₂ then e₁ else e₂
Instances For
The transported anti set, exactly: the two new chords' low ends, each present exactly when it was high in its old chord.
The flip count of a separated canonical step: the four-label indicator sum — the exact left side of the parity identity.
Canonicality and the summand cross a MatchEq unchanged (the
unsigned endpoint transfer).
The paired step without the chord signs: within a block the pairing returns, so the two path signs agree and cancel.
Equations
- One or more equations did not get rendered due to their size.
Instances For
The signed and unsigned paired steps coincide.