There are four troll brothers – Wudhor, Xhaqan, Yijlob, and Zrowag.
- Wudhor always says the truth.
- Xhaqan always lies.
- Yijlob lies or says the truth unpredictably.
- Zrowag is deaf and never answers.
You must ask these brothers four YES/NO questions (one troll per question), and figure out their names. What questions would you ask?
Source: Puzzling StackExchange