4165 — The Terminal Interaction-Net Presentation Bifurcates at Valuation Four
Claim under test
Entry 4160 required a terminal mixed-Rees presentation before fitting another equality-costalk coordinate. The first finite gate is whether the source-derived two-adic elimination admits one fixed pivot chart through the grade where the terminal classes attach.
Frozen computation
The source-fixed structural presentation was unchanged:
- matrix size ;
- fixed denominator on every de Rham row;
- multiplication rows retain source units;
- -depth ;
- labelled denominator depth ;
- ambient degree .
The same sparse elimination algorithm was applied at the equality-locus points and . These points have different terminal Smith valuations, respectively and .
Common pre-bifurcation object
After valuations , both fibers have:
- cumulative detected rank ;
- exactly residual rows;
- exactly active original columns;
- identical cumulative pivot schedule;
- identical labelled active-column support.
Thus the post-valuation- object is a common rank-four terminal presentation. It is the latest fiberwise reduction stage that can be lifted without choosing a kinematic pivot chart.
Valuation-four bifurcation
Both fibers add rank two at valuation , but only one pivot is common:
| role | original column | source label |
|---|---|---|
| common pivot | 2178 | [3,2,2,2,2,2,[1,5]] |
| -only pivot | 1947 | [3,2,1,1,1,1,[14,0]] |
| -only pivot | 2224 | [3,2,2,2,2,2,[5,1]] |
The resulting tails are not the same presentation:
| point | residual rows | active columns |
|---|---|---|
| 155 | 55 | |
| 143 | 42 |
The active support is a strict subset of the support. Therefore the divergence is not merely a different numerical value on a fixed two-generator matrix; the specialized elimination itself changes chart at valuation .
Narrow conclusion
There is no single fixed pivot schedule through valuation on the tested equality locus.
The source-derived object to lift is the common post-valuation- presentation. The valuation- pivot exchange is evidence for an atlas of terminal reduction charts, not evidence for either pivot label as a preferred equality coordinate.
This sharpens Entry 4160: the varying fifth-order attachment is encoded in the determinantal geometry of the common rank-four tail. It is not readable from one specialized Smith basis.
Next falsifier
Lift the common tail over the unspecialized local parameter ring while retaining its original column labels. Compute the rank-two valuation- determinantal ideal before choosing either pivot chart.
Accept a terminal coordinate only if a source-derived Fitting generator or invariant ideal controls both specialized charts and reproduces the observed terminal valuations. A coordinate obtained from either column 1947 or column 2224 alone is inadmissible.