Positive and negative example
Both positive and negative examples are useful in learning.
- in math: examples and counterexamples of objects
- whitelists vs blacklists
- in "Unteachable Excellence" Eliezer Yudkowsky makes the point that in some cases it is easier to teach what not to do (negative examples; e.g. listing out various failure modes) than it is to teach what to do (positive examples; e.g. verbalizing hard-to-articulate intuitions)