# Comparing Fable 5 and GPT-5.6 Sol on an NP-Hard Problem with a Goal Prompt

A developer tested two AI models, Fable 5 and GPT-5.6 Sol, on an NP-hard computational problem. The experiment explored whether adding a "/goal" directive improves the model's ability to solve the problem. This matters as it investigates how prompt engineering affects performance on complex tasks.

**Importance:** 3/5

## Sources

### Technology
- [Hacker News](https://charlesazam.com/blog/fable-5-gpt-5-6-sol-goal/) — Sat, 18 Jul 2026 11:00:29 +0000