How to prove that a problem is NP complete?
Under "2) Prove it's NP-hard."
This involves getting a known NP-complete problem like SAT (the set of boolean expressions in the form "(A OR B OR C) AND (D OR E OR F) AND ..." where the expression is satisfiable (ie there exists some setting for these booleans which makes the expression true).
The example accidentally implies the format for 3SAT, and it's never actually specified that the formula should be in CNF. I first used this answer when discovering how to prove NP-completeness, and was thrown off since I've heard of SAT and 3SAT but was not completely solid on the definitions.
My edit was too minor, so I'm asking someone who has full editing privileges to make a small change to clear up the confusion.