Completes the all/no/some square. `some` is read for the first time:
"All mammals are vertebrates. Some whales are mammals. Therefore some
whales are vertebrates." is decided entailed; "All unicorns are horned.
Therefore some unicorns are horned." is decided unsettled, with the
no-existential-import reading disclosed in the surface.
Mechanism (generate/proof_chain/exist.py): v5-VP's per-individual
lowering over a domain widened by one Skolem witness per existential
premise and — the load-bearing part — one ARBITRARY element per
existential conclusion, at which every universal still instantiates and
about which no premise asserts anything. Refuting an existential means
deriving a universal, and the arbitrary element is what makes that
derivation genuine instead of an assumption of domain closure: without
it "Rex is a wolf. Rex is not tame. Therefore some wolves are tame."
reads as REFUTED from a domain of one wolf. With it, UNKNOWN.
Four `en_exist_*` bands earned SERVE at 720x wrong=0 on the first arena
seal (25-band ledger); the 32-case hand-authored v2_exist split passed
32/32 first run; full lane 166/166 wrong=0 across six splits.
Also fixes a wrong-answer path this work uncovered in Band v1b
(ADR-0261 §5.1): `to_syllogism` FILTERED premises it could not express
out of the projection and answered from the remainder, so "Aristotle is
a philosopher. All philosophers are scholars. Therefore some scholars
are philosophers." lost its only witness and was served "that doesn't
follow". It now refuses — matching its propositional sibling
`to_deductive_logic`, which always has — and the argument falls through
to the bands that can hold a singular fact. The categorical band
re-earned SERVE 720/720 after the change; both examples are pinned as
regression cases.
Promotion: `ds-mem-0020` declined -> unknown (ADR-0258's existential
scope-out, now read; an anonymous witness never transfers to a named
individual, so UNKNOWN is its honest verdict, not entailed).
[Verification]: core test --suite deductive 232 passed; reader tests
33/33; register+surface tests 52 passed; arena 25 bands x 720 wrong=0
(all SERVE); lane 166/166 wrong=0; lane SHAs 9/10 match (public_demo
drift is pre-existing on the base commit and unrelated — evidence in
the Tier-S brief).
Composes v2-EN's connective grammar (if/then, or, and, either) with
v3-MEM's singular-membership sentence reading over one shared
per-individual atom space, so "If Socrates is a man then Socrates is
mortal. Socrates is a man. Therefore Socrates is mortal." decides — the
exact gap ADR-0258 §6.1 reserved. Genuinely fuses the two mechanisms: a
bare universal's instantiated atom can unify (via the same closed
morphology relation) with a connective leaf's atom, deciding arguments
neither band alone could.
- generate/proof_chain/cond_member.py: new reader. A sentence is checked
for a connective token BEFORE the universal-lead check (so a stray
connective can never leak into an opaque name/class run); reuses v3-MEM's
own _parse_singular/_parse_universal verbatim (already negation-aware,
so no separate negation layer is needed, unlike v2-EN's opaque minter).
Four new shape-bands (fused/disjunctive/chain/conditional), each earning
its own SERVE license.
- chat/deduction_surface.py: new fallback tier tried strictly after v3-MEM
— pure widening, every previously-served argument stays byte-identical.
- evals/deduction_serve/practice/gold.py: 4 new synthetic template groups
(20 templates), reusing the v3-MEM case generator; intended formulas
cross-checked against the independent oracle (INV-25).
- evals/deduction_serve/v2_condmem/: 26 hand-authored real-English cases,
content-disjoint from the synthetic corpus.
- ds-mem-0024 promoted declined -> unknown (not entailed — the antecedent
is never asserted in that text; this is the first promotion in the
corpus that doesn't land on entailed).
- Ledger re-sealed to 17 bands; deduction_serve_v1 lane SHA re-pinned
(surgical single-line edit, not a blanket --update).
Verification: core test --suite deductive 160 passed (31 new reader
tests); practice arena 17 bands x 720 wrong=0, all SERVE-licensed; lane
splits v1 28/28, v2_en 26/26, v2_member 26/26, v2_condmem 26/26; smoke 180
passed; warmed_session 10 passed. Flag deduction_serving_enabled stays
default-off.
