core practice · coding problem
Perplexity from average NLL
Average negative log-likelihood per token = 2.3 nats. Compute perplexity = exp(NLL).
The mechanism
A language model does one thing: predict the next token given the ones before it. Chat, code, reasoning — all of it is built on top of this single objective.
Expected evidence
PPX ≈ e^2.3 ≈ 9.97.
Try this drill in the practice workspace →
Hints when you need them
- Perplexity is exp of average NLL.
- Lower is better.