Wednesday 28 October 2026 · The robots · Steady
Kind of thinking: DeductionYukti #19 was a Steady robots puzzle, the puzzle for Wednesday 28 October 2026. Yukti, a daily logic puzzle at playyukti.com, gives everyone the same puzzle each day. Here is the puzzle, and its shortest route with the reason for every step.
The puzzle
Which robots are faulty?
In this workshop, honest robots always tell the truth and faulty robots always lie. Mark each robot. Every mark must be a certain deduction, not a guess.
- Bolt says: “Spark and I are the same kind.”
- Spark says: “At least 2 of us are faulty.”
- Widget says: “Exactly one of us is honest.”
- Pixel says: “Spark is honest.”
What is the shortest route?
4 marks. Each step says why it's certain.
- 1
Spark is honest.
Bolt's words settle it, whether Bolt is honest or faulty.
- 2
Widget is faulty.
If Widget were honest, Widget's words would be false, but honest robots never lie.
- 3
Pixel is honest.
If Pixel were faulty, Pixel's words would be true, but faulty robots never tell the truth.
- 4
Bolt is faulty.
Spark's words settle it, whether Spark is honest or faulty.
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