Motivating Example

The Venezuelan car manufacturer "Sucre" has been developing a futuristic electric car, called the Quipos. The Quipos has only three digital control circuits: the Energy Control Circuit (ECQ), the Wheel Control Circuit (WCQ), and the Human Haptics Detection (HHD) circuit (don't blame me for their strange acronyms). During development one of the circuits was repeatedly sending faulty signals to the WCQ, causing it to fail, with corresponding downstream impact on the car's self-steering and automatic braking features. The engineers needed to determine which circuit was sending the faulty signals to the WCQ. The following facts were known about the signals being sent between the circuits:

• A sending circuit causes a receiving circuit to fail by sending it (faulty) signals.
• A sending circuit never uses more power than the receiving circuit.
• The ECQ never sent signals to circuits that the WCQ sent signals to.
• The WCQ sent signals to all the circuits except the HHD.
• The HHD sent signals to all the circuits that did not use more power than the WCQ.
• The HHD sent signals to all the circuits that that the WCQ sent signals to.
• No circuit sent signals to every circuit.