/proof-theory

name: proof-theory
description: "Problem-solving strategies for proof theory in mathematical logic"
allowed-tools: [Bash, Read]

Proof Theory

When to Use

Use this skill when working on proof-theory problems in mathematical logic.

Decision Tree

1. **Proof Strategy Selection**

• Direct proof: assume premises, derive conclusion
• Proof by contradiction: assume negation, derive false
• Proof by cases: split on disjunction
• Induction: base case + inductive step

2. **Structural Induction**

• Define well-founded ordering on structures
• Base: prove for minimal elements
• Step: assume for smaller, prove for current
• `z3_solve.py prove "induction_principle"`

3. **Cut Elimination**

• Gentzen's Hauptsatz: cuts can be eliminated
• Subformula property: only subformulas appear
• Useful for proof normalization

4. **Completeness/Soundness Check**

• Soundness: if provable then valid
• Completeness: if valid then provable
• `z3_solve.py prove "soundness_theorem"`

5. **Proof Verification**

• Check each step follows from rules
• Verify dependencies are satisfied
• `math_scratchpad.py verify "proof_steps"`

Tool Commands

Z3_Induction_Base

uv run python -m runtime.harness scripts/cc_math/z3_solve.py prove "P(0)"

Z3_Induction_Step

uv run python -m runtime.harness scripts/cc_math/z3_solve.py prove "ForAll([n], Implies(P(n), P(n+1)))"

Z3_Soundness

uv run python -m runtime.harness scripts/cc_math/z3_solve.py prove "Implies(derivable(phi), valid(phi))"

Math_Verify

uv run python -m runtime.harness scripts/cc_math/math_scratchpad.py verify "proof_structure"

Cognitive Tools Reference

See `.claude/skills/math-mode/SKILL.md` for full tool documentation.