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P vs NP in QLF

Status: p_vs_np_proof_in_progress — a reformulation. Contrast (once): the classical P vs NP question is not settled here. What is proven (the reformulation): the generate/verify asymmetry on real theorems — the realized set is the O(n) verify-filter of the candidates, with size C(2n,n) (lean/QLF_PvsNP.lean). The gap: the formal complexity separation is the one bridge axiom generate_not_reducible_to_verify, over an abstract cost model (QLF has no machine model). P vs NP is a finitary statement about computation, not a known independence phenomenon — so "ZFC's defect" does not apply (that is for halting / Busy Beaver). So: contrast (classical, not settled) → the proven asymmetry → the named bridge. See Open_Problems.md, Continuum_Choice_Fallacy.md.

1. The classical problem

The most famous Millennium Prize Problem: is P = NP? Is every problem whose solution can be verified quickly (NP) also solvable quickly (P)? Equivalently, is search no harder than checking? The expected answer is P ≠ NP — that finding a needle is fundamentally harder than recognising one — but no proof is known, and the difficulty is that lower bounds on computation are notoriously hard to establish.

2. The QLF substrate already separates the two operations

QLF's engine is literally a generate-then-verify machine, and the two halves have visibly different cost:

  • Generate (search). The QuCalc expansion enumerates the possibility space of phase-string histories. At depth 2n the branching is exponential: there are 4^n length-2n twist strings before any filtering. This is the modal-realist space — all logically admissible histories exist a priori (Philosophy.md); finding the physical ones is a search through an exponentially large tree.
  • Verify (check). ZFA closure is a linear-time predicate: walk the string once and check count_pos = count_neg (and Pauli closure, which count_balanced_pauli_closed shows is entailed). qlf_universality (lean/QLF_Universality.lean) is the statement that this O(n) closure check is exactly what selects the physical (terminating) computations from the full ruliad. Verification is cheap; generation is not.

So in QLF the P/NP boundary is the boundary between the ZFA filter and the QuCalc generator. Verification = "is this history a ZFA closure?" (P). Search = "produce a ZFA closure with property X" (NP). They are different objects in the framework, not two views of one.

3. The structural reading: why the asymmetry should be irreducible

QLF's selection principle gives a reason the asymmetry does not collapse:

  • Closure is global; it cannot be assembled greedily. A ZFA closure is balanced as a whole (and Pauli-closed in order); a prefix of a closure is generally not a closure (the half-spin pruning full_zeno_prune discards unclosed fractions). There is no local certificate that a partial history can be extended to a closure with a target property — which is precisely the obstruction to turning fast verification into fast search.
  • Of the exponentially many depth-2n histories, exactly C(2n,n) are ZFA-balanced (find_stable_states_length_even, lean/QLF_QuCalc.lean) — a ~4^n/√n fraction. The solutions are dense enough to verify one instantly yet spread through the tree with no shortcut to the one you want.
  • This is the same wall as the Busy-Beaver / ZFC ultraviolet catastrophe (Active_Inference_Mathematics.md §6, ReverseMathematics.md): QLF lives at the RCA₀ floor, below the uncomputable. Within that floor, the cost of constructing a witness is not bounded by the cost of recognising one — the generator and the filter are genuinely separate machines.

QLF therefore leans P ≠ NP: search through the possibility space is structurally heavier than the linear closure check, and the framework exhibits no mechanism that reduces one to the other.

4. Where the boundary sits

A structural asymmetry is not a complexity-theoretic lower bound. Turning "closure is global and has no greedy certificate" into "no polynomial-time algorithm decides SAT" is the genuinely hard analytic/combinatorial step — the same kind of RCA₀ → higher-strength crossing QLF marks elsewhere with an explicit axiom. QLF makes the generate/verify gap concrete and gives a substrate reason it should not close; the formal separation P ≠ NP is the remaining step, over an infinite computational model — the sector where ZFC is itself proven to fail (Gödel/Turing/Busy Beaver). It is ZFC's defect, not a gap in this reading.

This is Lean-anchored in lean/QLF_PvsNP.lean: the two halves that are QLF facts are proven by reusing verified theorems — the realized set IS the O(n) verify-filter of the generated candidates (realized_is_verify_filter, definitional) and its cardinality is the genuine C(2n,n) (realized_count_eq_central_binomial, reusing find_stable_states_length_even) — while the separation itself is the single explicit boundary axiom generate_not_reducible_to_verify over an abstract PTime/search cost model, with the p_vs_np_proof_in_progress status marker.

5. Epistemic stance

Within QLF's frame, P ≠ NP is the computational face of the same principle as the ZFC ultraviolet catastrophe: possibility is cheap to enumerate and cheap to check, but expensive to select. The universe is the ZFA-closed subset of an exponential possibility space, and there is no free lunch that hands you the closure you want without searching for it. The circuit lower bound is the remaining step, carried by the one bridge axiom generate_not_reducible_to_verify over an abstract cost model. P vs NP is a finitary statement about computation — not a known independence phenomenon — so the "ZFC's defect" framing (which belongs to genuine uncomputability: halting, Busy Beaver) does not apply here. The honest reading: the substrate-constructive generate/verify asymmetry is proven; the formal separation is the named open bridge — genuine progress, not a finished classical proof.

References

  • S. A. Cook, The complexity of theorem-proving procedures, Proc. 3rd ACM STOC (1971) 151–158 — NP-completeness.
  • L. A. Levin, Universal sequential search problems, Probl. Peredachi Inf. 9 (1973) — independent formulation.
  • R. M. Karp, Reducibility among combinatorial problems, in Complexity of Computer Computations (1972) 85–103.
  • S. Cook, The P versus NP Problem — Clay Mathematics Institute (official problem description). https://www.claymath.org/millennium-problems/