921 — The Diagonal and Off-Diagonal Lines Remain Independent at the Deeper Corner
Comparison problem
The diagonal flag
has a rank-one first conormal grade from Entry 912. The off-diagonal flag
has the Cartier-twisted Rees line of Entries 918–920.
Their ranks agree, but this does not type a comparison. The first admissible test is to restrict both source-derived representatives to their actual common deeper corner in the same transition target.
Forced fourth normal
Use multiplicative channel coordinates
The simultaneous conditions
force
Therefore setting only (X=1) after the off-diagonal Rees restriction does not reach the common corner. The (Z)-normal is mandatory.
Inherited lattice regularizations
The off-diagonal exceptional line carries the factor (1/U), so its regular generator is obtained by multiplying by (U).
The diagonal first-conormal line develops a simple pole at (Z=1). Its inherited regular generator is therefore obtained by multiplying by (Z-1) before specialization.
Both operations use existing source equations. No fitted scalar is introduced.
Exact common-corner comparison
After these two regularizations, the diagonal generator has twelve nonzero matrix entries and target direction
whereas the off-diagonal generator has six nonzero entries and target direction
The exact (2\times2) minor in the first source column is
which is generically nonzero. Hence
The identity comparison in the common transition target does not identify the two lines.
Narrow conclusion
The diagonal conormal line and the off-diagonal Rees line are distinct filtered coefficient directions even at their shared deeper corner:
This rules out assembling them by rank matching or by treating the off-diagonal line as another chart of the diagonal line. It does not rule out a nontrivial differential between them.
No such differential is supplied by the frozen basis-transition matrix: it provides the two sections but no map changing filtration type. A comparison remains untyped until derived from a marked-incidence differential, a localization triangle, or a Rees specialization morphism.
Next falsifier
Search the frozen six-point marked-incidence complex for a boundary operator whose source and target are exactly these two filtered lines. If one exists, compute its common-corner scalar and symmetry character. If none exists, retain the rank-two direct sum and record that the proposed mixed differential is absent at this level.