twoThreePrimeMixedDirection
plain-language theorem explainer
Defines the mixed ratio orbit at the composite 2·3 under a two-adic axis twist: reciprocal on the 2-branch and identity on the 3-branch, hence the orbit of 3/2. Cited wherever two-adic twist characters are tested against prime-pair product costs. Construction is a one-line product of the reciprocal of the two-prime direction with the three-prime direction.
Claim. The mixed direction at the composite $2\cdot 3$ is the rational orbit $\mathrm{recip}(2)\cdot 3$, i.e. the orbit of $3/2$, obtained by taking the reciprocal of the canonical two-prime direction and multiplying by the canonical three-prime direction.
background
In the primitive recognition calculus, rational comparison data live in RatioOrbit: an integer numerator over a nonzero distinction-nat denominator (K4.7). Reciprocal on ratio orbits is total and sends zero to zero, matching the usual map on $\mathbb{Q}$ (K4.12). The dual-recognition symmetry on positive reals is the involution $\iota(x)=x^{-1}$.
The module builds native cost uniqueness tests by comparing characters and costs on prime directions and their composites. The two-prime and three-prime directions are the canonical orbits of the primes $2$ and $3$. A two-adic axis twist flips the $2$-branch while leaving other prime branches fixed; at the composite $2\cdot 3$ that forced mixed image is exactly $3/2$.
proof idea
One-line definitional construction: multiply the reciprocal of the two-prime direction by the three-prime direction inside the ratio-orbit monoid. No tactics or lemmas beyond the constructors RatioOrbit.mul, RatioOrbit.recip, and the two named prime directions.
why it matters
This orbit is the concrete mixed image that a two-adic axis twist character must hit at the composite $2\cdot 3$. Downstream theorems use it to show the twist character sends that composite to $3/2$ (cross-equality), that the mixed direction is not cross-equal to the plain composite $2\cdot 3$, and that two-adic generated native costs and twist characters fail prime-pair product cost consistency and calibration. Those failures feed the refutation of the native cost uniqueness target: uniqueness fails once two-adic axis twists are admitted. In the broader forcing chain this is local scaffolding for J-cost uniqueness (T5) and the recognition composition law, by ruling out non-canonical cost factors on small prime composites.
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