The scene
Historical Games Room · Display caseA token from an antique game disappears from a display case. Its drawer checks two lights after each button press.
Three people gave a demonstration. Reconstruct the order and follow the changes to discover which press allowed it to open.
What we know for certain
One person removed the token during their demonstration. Each person pressed their own button exactly once. The drawer allows the token to be removed only at the check following that press and locks again at the end of the turn. There were no other accesses.
The three accounts
Ada Roca
Instructor«I used my button and handed over the station. I did not take any piece.»
Belén Soto
Researcher«My demonstration was the last of the session.»
Cris Vela
Restorer«I went in after Ada and followed the instructions.»
Examine the evidence
0 of 5 openedOpening these five clues does not cost points.
01The opening condition
The drawer opens only when the left light is off and the right light is on. Every other combination keeps it shut.
02The initial state
Both lights were off before the first visitor. They retain their latest state between turns.
03The three functions
Ada's button toggles only the left light; Belén's, only the right; Cris's toggles both. To toggle means to change on to off or off to on.
04The recorded order
Ada entered before Cris. Belén was last. Each of the three people had exactly one turn.
05One check per person
There was one button press per turn. Nobody could open the drawer before pressing or after their demonstration.