Explicit Right-Kernel Supports in Two-Prime Rédei Layers: An r4=1 Criterion and Conditional CFRAC Redundancy

We give an explicit treatment of right-kernel supports in two-prime pure Rédei layers for discriminants D = 4Ap1p2, with emphasis on the case r4 = 1. A unified four-bit formula describes the column-normalized 4-by-4 Rédei matrix, and an exhaustive classification identifies the nontrivial right-kernel support. In particular, the relevant squarefree support need not be all of p1p2. Proper supports and supports involving A occur in explicitly characterized cases. Under the stated hypothesis Qm divides 2N, continued-fraction central data identify the principal kernel direction and reduce the effective Artin–Rédei criterion to a single symbol evaluation. Classical Rédei–Reichardt theory, the general Artin–Rédei formalism, and the associated rank formulas are used as prior input and are explicitly attributed. Version 1.1.0 note: This substantially revised version supersedes Zenodo record 21950745 (v1.0.0) in the same concept-DOI series. It sharpens the novelty boundary, reorganizes the principal results, expands attribution and proofs, makes the CFRAC hypothesis explicit, and strengthens the reproducibility documentation. The earlier record is not withdrawn for a mathematical error. Zenodo record 21962291 is a duplicate archival deposit of the v1.0.0 research content.