---
id: wiki-2026-0508-problem-solving-skills
title: Problem Solving Skills
category: 10_Wiki/Topics
status: verified
canonical_id: self
aliases: [Problem Solving, 문제 해결 능력, debugging skills]
duplicate_of: none
source_trust_level: A
confidence_score: 0.9
verification_status: applied
tags: [meta, debugging, engineering, methodology]
raw_sources: []
last_reinforced: 2026-05-10
github_commit: pending
tech_stack:
  language: meta
  framework: methodology
---

# Problem Solving Skills

## 매 한 줄
> **"매 problem 정의가 매 solution의 매 절반"**. Problem solving은 매 ill-defined situation을 매 well-defined sub-problems으로 매 decompose하고 매 hypothesis-test loop으로 매 narrow down하는 매 transferable skill set. Polya (1945) 4-step부터 매 modern debugging 까지 매 동일한 backbone.

## 매 핵심

### 매 Polya 4-step (1945)
1. **Understand**: 매 input/output/constraint 매 명시.
2. **Plan**: 매 known similar problem과 매 mapping.
3. **Execute**: 매 plan 매 step-by-step.
4. **Review**: 매 result verify, 매 generalize.

### 매 Debugging 전용 loop
- **매 Reproduce**: 매 minimal repro case.
- **매 Bisect**: 매 git bisect / binary search.
- **매 Hypothesize**: 매 1개 변수만 매 변경.
- **매 Verify**: 매 test 매 추가.
- **매 Postmortem**: 매 root cause + prevention.

### 매 응용
1. Production incident response (5-why).
2. Algorithm design (decomposition + invariants).
3. LLM prompt debugging (delta isolation).

## 💻 패턴

### Minimal repro extraction
```python
# Bisect a failing input down to minimal case
def minimal_repro(input_list, fails):
    while True:
        for i in range(len(input_list)):
            candidate = input_list[:i] + input_list[i+1:]
            if fails(candidate):
                input_list = candidate
                break
        else:
            return input_list
```

### Git bisect automation
```bash
git bisect start HEAD v1.0.0
git bisect run pytest tests/test_regression.py::test_bug
# 매 Bisect 자동 종료 → first-bad-commit 매 출력
```

### 5-why root cause
```yaml
# postmortem.yaml
incident: api 500 spike
why_1: db connections exhausted
why_2: connection leak in /search handler
why_3: exception bypassed `with` cleanup
why_4: custom context manager swallowed asyncio.CancelledError
why_5: copy-pasted snippet from Stack Overflow without review
fix: replace with asynccontextmanager + add lint rule
```

### Hypothesis-driven test
```python
# Change ONE variable per iteration
import time
def measure(config):
    t = time.time(); run(config); return time.time() - t

base = {"batch": 32, "workers": 4, "cache": True}
for k in base:
    cfg = {**base, k: not base[k] if isinstance(base[k], bool) else base[k]*2}
    print(k, measure(cfg))
```

### Rubber-duck logger
```python
def trace_state(label, **vars):
    print(f"[{label}]", " | ".join(f"{k}={v!r}" for k, v in vars.items()))

trace_state("before-loop", i=0, total=len(data), seen=set())
```

## 매 결정 기준
| 상황 | Approach |
|---|---|
| Bug 매 reproducible | Bisect + minimal repro |
| Bug 매 intermittent | Logging + statistical test |
| Algorithm 매 unknown | Polya + analogy from known |
| Production incident | 5-why + postmortem |

**기본값**: Reproduce → Bisect → Hypothesize → Verify → Document.

## 🔗 Graph
- 부모: [[Debugging]]
- 변형: [[Polya-Method]] · [[Bisect]]
- 응용: [[Postmortem]]
- Adjacent: [[Scientific-Method]]

## 🤖 LLM 활용
**언제**: 매 ill-defined task decomposition, 매 stuck-state escape, 매 LLM prompt 디버깅.
**언제 X**: 매 trivial 1-line typo (overhead).

## ❌ 안티패턴
- **매 Shotgun debugging**: 매 random 변경 후 매 동작하면 commit.
- **매 Symptom-only fix**: 매 root cause 무시.
- **매 No repro**: 매 "내 환경에선 됨".
- **매 Heisenbug 회피**: 매 logging 추가하면 매 사라지는 bug 매 무시.

## 🧪 검증 / 중복
- Verified (Polya "How to Solve It" 1945, Zeller "Why Programs Fail" 2nd ed.).
- 신뢰도 A.

## 🕓 Changelog
| 날짜 | 변경 |
|---|---|
| 2026-05-08 | Phase 1 |
| 2026-05-10 | Manual cleanup — Polya + debugging loop + repro/bisect patterns |
