---
name: Missing × Executable 2-axis classification (Q1-Q4)
description: 4-quadrant classification scheme from 2026-04-24 METADB v2.3 — use when classifying any entry for its strategic quadrant
type: feedback
originSessionId: 2812f631-04af-4dd8-a8cd-4f872e1e1383
---
**Rule**: Every non-Tier-1 entry should carry `missingExecutableMeta` with 4-quadrant classification. Tier 1 paperCandidate entries also carry it.

**Why**: 藤本さん 2026-04-24 session で提案された基礎的 2 軸 — 「足りないもの」 × 「実行可能 vs 不可能と思われる」. Rei-AIOS の全 entries が共通して持つ meta-layer で、戦略的象限判断に使う。この 2 軸が META-DB foundation になっている。

**How to apply**:

## Axis A: missingStatus ∈ {fully-missing, partially-addressed, addressed}

- **fully-missing**: gap 未着手、tool 未存在、curriculum 未設計
- **partially-addressed**: 部分解決あり (Paper 133 partial formalization 型)
- **addressed**: 解決済 / 完成 tool / 実施中 curriculum

## Axis B: possibilityStatus ∈ {thought-impossible, thought-possible-undone, partially-done, executable-today}

- **thought-impossible**: Collatz / Riemann / Hard Problem 級の「不可能と思われる」
- **thought-possible-undone**: 実行可能なはずだが未着手
- **partially-done**: 部分的進行中
- **executable-today**: すぐ実行できる (Mathlib PR 候補レベル)

## Quadrants

```
                    executable-today
                          │
     Q3: Present+Exec    │    Q1: Missing+Exec ★
     (完成 tool/theorem) │    (QUICK WINS)
                          │
  addressed ────────────┼──────────── fully-missing
                          │
     Q4: Present+Imp     │    Q2: Missing+Imp ★
     (partial closures) │    (RESEARCH FRONTIER)
                          │
                    thought-impossible
```

- **Q1 (Missing+Executable)**: immediate action candidates, Mathlib PR material, Paper 133 Tier-1 closure 型
- **Q2 (Missing+Impossible-seeming)**: Rei-AIOS 最大価値領域 — Collatz / D-FUMT₈ completeness / Hard Problem / Peace-axiom formal check
- **Q3 (Present+Executable)**: 完成品 — Mathlib theorems, production tools, completed papers
- **Q4 (Present+Impossible-seeming)**: 部分突破済み — Papers 133/135/137 の partial closures of "impossible" problems

## Distribution (2026-04-24)

Q1=99 / Q2=18 / Q3=4 / Q4=27 / untagged T1=2,564

## Additional schema (superCapability — STEP 999c 追加)

```json
"missingExecutableMeta": {
  ...
  "superCapability": {
    "builtTools": ["rei-tool-..."],        // already addresses this entry
    "plannedTools": ["rei-tool-..."],      // planned future tool
    "breakthroughNeeded": ["..."]          // concrete breakthroughs required
  }
}
```

This 3-field extension links the gap → tools triangle: what we built, what we plan, what's still blocking.

## Category→quadrant heuristics (when auto-tagging)

| Entry type | Typical quadrant |
|-|-|
| Tier 1 paperCandidate with famousHardCap < 0.2 | Q2 |
| Tier 1 paperCandidate with famousHardCap > 0.5 | Q1 |
| Tier 2 Rei invention | Q4 (conjectured but unproven) |
| Tier 3 Claude discovery | Q4 (observed, partial) |
| Tier 4 gap (tractability=blocked) | Q2 |
| Tier 4 gap (tractability=active-research) | Q1 |
| Tier 5 tool (phase=production) | Q3 |
| Tier 5 tool (phase=prototype/alpha) | Q4 |
| Tier 6 strategy (immediate/short-term) | Q1 |
| Tier 6 strategy (long-term) | Q1→Q2 moving |

## Reference

- Schema detail: `data/open-problems/INDEX.json` `quadrantDescription` field
- Session origin: `project_session_20260424_metadb_v23_strategy.md`
- Elevator pitch incorporating this: `feedback_elevator_pitch_core_value_proposition.md`