Suppose you have a set membership question. If you approximate yes, you do a more complex inquiry to grab details. If you approximate no, you tell the user no,

Suppose you have a set membership question. If you approximate yes, you do a more complex inquiry to grab details. If you approximate no, you tell the user no, don't know that face [answer, command, etc]. So this is ripe for approximate methods as you can tune to get very few false negatives (respond no when it's really yes), but allow a healthy dose of false positives.