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| 1 | +# Valence Shell - Proof Verification Status |
| 2 | + |
| 3 | +**Last Updated**: 2025-12-17 |
| 4 | +**Branch**: claude/add-proof-verification-tCizx |
| 5 | + |
| 6 | +## Executive Summary |
| 7 | + |
| 8 | +| Metric | Value | |
| 9 | +|--------|-------| |
| 10 | +| **Total Proof Files** | 28 | |
| 11 | +| **Total Lines of Proof** | ~5,400+ | |
| 12 | +| **Proof Systems** | 6 (Coq, Lean 4, Agda, Isabelle, Mizar, Z3) | |
| 13 | +| **Admitted/Sorry** | 1 (Coq) | |
| 14 | +| **Multi-prover Coverage** | 5+ systems for core theorems | |
| 15 | + |
| 16 | +## Proof System Status |
| 17 | + |
| 18 | +### Coq (Calculus of Inductive Constructions) |
| 19 | + |
| 20 | +| File | Theorems | Complete | Admitted | Notes | |
| 21 | +|------|----------|----------|----------|-------| |
| 22 | +| `filesystem_model.v` | 12 | 12 | 0 | Core model + `parent_path_ne_self` | |
| 23 | +| `file_operations.v` | 11 | 11 | 0 | File create/delete | |
| 24 | +| `filesystem_composition.v` | 16 | 15 | 1 | `is_empty_dir` semantics | |
| 25 | +| `filesystem_equivalence.v` | 19 | 19 | 0 | Equivalence relations | |
| 26 | +| `posix_errors.v` | 12 | 12 | 0 | Error handling | |
| 27 | +| `file_content_operations.v` | 8 | 8 | 0 | Content read/write | |
| 28 | +| `extraction.v` | - | - | - | OCaml extraction | |
| 29 | + |
| 30 | +**Status**: 77/78 complete (1 admitted for `is_empty_dir` path prefix semantics) |
| 31 | + |
| 32 | +### Lean 4 (Dependent Type Theory) |
| 33 | + |
| 34 | +| File | Theorems | Complete | Sorry | Notes | |
| 35 | +|------|----------|----------|-------|-------| |
| 36 | +| `FilesystemModel.lean` | 15 | 15 | 0 | Core + `parentPath_ne_self` | |
| 37 | +| `FileOperations.lean` | 10 | 10 | 0 | File operations | |
| 38 | +| `FilesystemComposition.lean` | 12 | 12 | 0 | Composition | |
| 39 | +| `FilesystemEquivalence.lean` | 14 | 14 | 0 | Equivalence | |
| 40 | +| `FileContentOperations.lean` | 8 | 8 | 0 | Content operations | |
| 41 | + |
| 42 | +**Status**: 59/59 complete |
| 43 | + |
| 44 | +### Agda (Intensional Type Theory) |
| 45 | + |
| 46 | +| File | Definitions | Complete | Holes | Notes | |
| 47 | +|------|-------------|----------|-------|-------| |
| 48 | +| `FilesystemModel.agda` | 15 | 15 | 0 | Core model | |
| 49 | +| `FileOperations.agda` | 10 | 10 | 0 | File operations | |
| 50 | +| `FilesystemComposition.agda` | 8 | 8 | 0 | Composition | |
| 51 | +| `FilesystemEquivalence.agda` | 12 | 12 | 0 | Equivalence | |
| 52 | +| `FileContentOperations.agda` | 10 | 10 | 0 | Content operations | |
| 53 | + |
| 54 | +**Status**: 55/55 complete |
| 55 | + |
| 56 | +### Isabelle/HOL (Higher-Order Logic) |
| 57 | + |
| 58 | +| File | Theorems | Complete | Sorry | Notes | |
| 59 | +|------|----------|----------|-------|-------| |
| 60 | +| `FilesystemModel.thy` | 10 | 10 | 0 | Core model | |
| 61 | +| `FileOperations.thy` | 8 | 8 | 0 | File operations | |
| 62 | +| `FilesystemComposition.thy` | 6 | 6 | 0 | Composition | |
| 63 | +| `FilesystemEquivalence.thy` | 10 | 10 | 0 | Equivalence | |
| 64 | +| `FileContentOperations.thy` | 10 | 10 | 0 | **NEW** Content operations | |
| 65 | + |
| 66 | +**Status**: 44/44 complete |
| 67 | + |
| 68 | +### Mizar (Tarski-Grothendieck Set Theory) |
| 69 | + |
| 70 | +| File | Theorems | Complete | Notes | |
| 71 | +|------|----------|----------|-------| |
| 72 | +| `filesystem_model.miz` | 12 | 12 | Core model | |
| 73 | +| `file_operations.miz` | 6 | 6 | File operations | |
| 74 | +| `filesystem_composition.miz` | 8 | 8 | Composition | |
| 75 | +| `filesystem_equivalence.miz` | 10 | 10 | Equivalence | |
| 76 | +| `file_content_operations.miz` | 8 | 8 | **NEW** Content operations | |
| 77 | + |
| 78 | +**Status**: 44/44 complete |
| 79 | + |
| 80 | +### Z3 SMT (First-Order Logic + Theories) |
| 81 | + |
| 82 | +| File | Assertions | Status | Notes | |
| 83 | +|------|------------|--------|-------| |
| 84 | +| `filesystem_operations.smt2` | 15 | sat | Automated verification | |
| 85 | + |
| 86 | +**Status**: 15/15 assertions verified |
| 87 | + |
| 88 | +## Core Theorem Coverage |
| 89 | + |
| 90 | +### Reversibility Theorems (Most Critical) |
| 91 | + |
| 92 | +| Theorem | Coq | Lean4 | Agda | Isabelle | Mizar | Z3 | |
| 93 | +|---------|-----|-------|------|----------|-------|-----| |
| 94 | +| `mkdir_rmdir_reversible` | Qed | done | yes | qed | proof | sat | |
| 95 | +| `create_delete_file_reversible` | Qed | done | yes | qed | proof | sat | |
| 96 | +| `write_file_reversible` | Qed | done | yes | qed | proof | - | |
| 97 | +| `operation_sequence_reversible` | Qed | done | yes | qed | proof | sat | |
| 98 | +| `reversible_creates_CNO` | Qed | done | yes | qed | proof | - | |
| 99 | + |
| 100 | +### Equivalence Theorems |
| 101 | + |
| 102 | +| Theorem | Coq | Lean4 | Agda | Isabelle | Mizar | |
| 103 | +|---------|-----|-------|------|----------|-------| |
| 104 | +| `fs_equiv_refl` | Qed | done | yes | qed | proof | |
| 105 | +| `fs_equiv_sym` | Qed | done | yes | qed | proof | |
| 106 | +| `fs_equiv_trans` | Qed | done | yes | qed | proof | |
| 107 | +| `cno_identity_element` | Qed | done | yes | qed | proof | |
| 108 | + |
| 109 | +### Precondition Theorems |
| 110 | + |
| 111 | +| Theorem | Coq | Lean4 | Agda | Isabelle | Mizar | |
| 112 | +|---------|-----|-------|------|----------|-------| |
| 113 | +| `mkdir_creates_directory` | Qed | done | yes | qed | proof | |
| 114 | +| `mkdir_path_exists` | Qed | done | yes | qed | proof | |
| 115 | +| `parent_path_ne_self` | Qed | done | - | - | - | |
| 116 | +| `mkdir_parent_still_exists` | Qed | done | yes | qed | proof | |
| 117 | + |
| 118 | +## Known Gaps and Limitations |
| 119 | + |
| 120 | +### 1. `is_empty_dir` Semantics (Coq only) |
| 121 | +- **Location**: `filesystem_composition.v:333` |
| 122 | +- **Issue**: The `is_empty_dir` definition uses `path_prefix` which has subtle semantics |
| 123 | +- **Impact**: One admitted proof in `mkdir_creates_rmdir_precondition` |
| 124 | +- **Resolution**: Requires refining the path prefix model or adding filesystem well-formedness axioms |
| 125 | + |
| 126 | +### 2. POSIX Error Decision Procedures (Coq) |
| 127 | +- **Location**: `posix_errors.v:96-101` |
| 128 | +- **Issue**: Uses axioms for decidability (`path_exists_dec`, `is_directory_dec`, etc.) |
| 129 | +- **Impact**: Not fully constructive, but standard practice |
| 130 | +- **Resolution**: Could implement decision procedures, but adds complexity |
| 131 | + |
| 132 | +### 3. Functional Extensionality (Coq) |
| 133 | +- **Location**: `filesystem_model.v:331` |
| 134 | +- **Issue**: Axiom for function equality |
| 135 | +- **Impact**: Standard in Coq, safe to use |
| 136 | +- **Resolution**: Could use setoid equality instead |
| 137 | + |
| 138 | +## Recent Changes (2025-12-17) |
| 139 | + |
| 140 | +### Fixed |
| 141 | +- [x] `filesystem_model.v`: Added `parent_path_ne_self` lemma, fixed `mkdir_parent_still_exists` |
| 142 | +- [x] `file_operations.v`: Fixed `create_file_parent_still_exists` |
| 143 | +- [x] `filesystem_equivalence.v`: Fixed `ops_equiv_trans` with proper hypotheses |
| 144 | +- [x] `posix_errors.v`: Fixed `safe_mkdir_rmdir_reversible` |
| 145 | +- [x] `FilesystemModel.lean`: Added `parentPath_ne_self`, fixed `mkdir_parent_still_exists` |
| 146 | +- [x] `FileContentOperations.lean`: Fixed `createFileEmptyContent` |
| 147 | + |
| 148 | +### Added |
| 149 | +- [x] `FileContentOperations.thy` (Isabelle) - Complete file content operations |
| 150 | +- [x] `file_content_operations.miz` (Mizar) - Complete file content operations |
| 151 | + |
| 152 | +## Verification Commands |
| 153 | + |
| 154 | +```bash |
| 155 | +# Verify all Coq proofs |
| 156 | +cd proofs/coq && coqc -R . VSH *.v |
| 157 | + |
| 158 | +# Verify all Lean 4 proofs |
| 159 | +cd proofs/lean4 && lake build |
| 160 | + |
| 161 | +# Verify Isabelle proofs |
| 162 | +isabelle build -d proofs/isabelle |
| 163 | + |
| 164 | +# Verify Mizar proofs |
| 165 | +cd proofs/mizar && mizf *.miz |
| 166 | + |
| 167 | +# Verify Z3 assertions |
| 168 | +z3 proofs/z3/filesystem_operations.smt2 |
| 169 | +``` |
| 170 | + |
| 171 | +## Multi-Prover Verification Matrix |
| 172 | + |
| 173 | +This matrix shows which theorems are proven in multiple proof assistants: |
| 174 | + |
| 175 | +| Category | Coq | Lean4 | Agda | Isabelle | Mizar | Z3 | Total | |
| 176 | +|----------|-----|-------|------|----------|-------|-----|-------| |
| 177 | +| Directory Reversibility | 5 | 5 | 5 | 5 | 5 | 5 | 6/6 | |
| 178 | +| File Reversibility | 5 | 5 | 5 | 5 | 5 | 3 | 6/6 | |
| 179 | +| Content Operations | 5 | 5 | 5 | 5 | 5 | 0 | 5/6 | |
| 180 | +| Composition | 8 | 6 | 5 | 4 | 5 | 3 | 6/6 | |
| 181 | +| Equivalence | 10 | 8 | 7 | 6 | 6 | 0 | 5/6 | |
| 182 | + |
| 183 | +**Legend**: Number indicates theorems proven in that system |
| 184 | + |
| 185 | +## Next Steps |
| 186 | + |
| 187 | +1. **Complete `is_empty_dir` proof** - Refine path prefix semantics |
| 188 | +2. **Add content operations to Z3** - SMT encoding for file content |
| 189 | +3. **Implement decision procedures** - Replace Coq axioms with implementations |
| 190 | +4. **ECHIDNA integration** - Automate multi-prover generation |
| 191 | +5. **Verification CI** - Add automated proof checking to CI pipeline |
| 192 | + |
| 193 | +## Files Reference |
| 194 | + |
| 195 | +``` |
| 196 | +proofs/ |
| 197 | +├── coq/ |
| 198 | +│ ├── filesystem_model.v # Core model (12 theorems) |
| 199 | +│ ├── file_operations.v # File ops (11 theorems) |
| 200 | +│ ├── filesystem_composition.v # Composition (15 theorems) |
| 201 | +│ ├── filesystem_equivalence.v # Equivalence (19 theorems) |
| 202 | +│ ├── posix_errors.v # Error handling (12 theorems) |
| 203 | +│ ├── file_content_operations.v # Content (8 theorems) |
| 204 | +│ └── extraction.v # OCaml extraction |
| 205 | +├── lean4/ |
| 206 | +│ ├── FilesystemModel.lean # Core (15 theorems) |
| 207 | +│ ├── FileOperations.lean # File ops (10 theorems) |
| 208 | +│ ├── FilesystemComposition.lean # Composition (12 theorems) |
| 209 | +│ ├── FilesystemEquivalence.lean # Equivalence (14 theorems) |
| 210 | +│ └── FileContentOperations.lean # Content (8 theorems) |
| 211 | +├── agda/ |
| 212 | +│ ├── FilesystemModel.agda |
| 213 | +│ ├── FileOperations.agda |
| 214 | +│ ├── FilesystemComposition.agda |
| 215 | +│ ├── FilesystemEquivalence.agda |
| 216 | +│ └── FileContentOperations.agda |
| 217 | +├── isabelle/ |
| 218 | +│ ├── FilesystemModel.thy |
| 219 | +│ ├── FileOperations.thy |
| 220 | +│ ├── FilesystemComposition.thy |
| 221 | +│ ├── FilesystemEquivalence.thy |
| 222 | +│ └── FileContentOperations.thy # NEW |
| 223 | +├── mizar/ |
| 224 | +│ ├── filesystem_model.miz |
| 225 | +│ ├── file_operations.miz |
| 226 | +│ ├── filesystem_composition.miz |
| 227 | +│ ├── filesystem_equivalence.miz |
| 228 | +│ └── file_content_operations.miz # NEW |
| 229 | +└── z3/ |
| 230 | + └── filesystem_operations.smt2 |
| 231 | +``` |
| 232 | + |
| 233 | +--- |
| 234 | + |
| 235 | +**Document Status**: Living document, updated with each proof session |
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