Friday Puzzler -- Light Switch

Hint and clarification

alexy

Abstraction does not help in solving this one.

"wile" in the original statement of the problem is a typo. Hopefully you read it as "while", but since puzzles sometimes have tricky wording, I wanted to clarify in case anyone was going down a rabbit hole trying to figure out what I meant by "wile" in this context.

Hint 2

alexy

I said abstraction doesn't help. Well, of course you have to abstract if you are not going to build the physical model. An abstraction is generally helpful in removing irrelevant information. E.g., you can ignore items not given in the problem, such as color of the room's walls. You also ignore certain features that would almost certainly be part of the real world. E.g., you probably viewed the walls of the room as merely opaque barriers without thickness (and that abstraction works fine here). But what makes this problem hard is that your abstraction/mental model almost certainly left out something key to solving this one.

Other abstractions you probably made in thinking about this problem were:

Each switch has exactly two states--open and closed

The light bulb has exactly two states--on and off

When you open the door, you can observe one thing--whether the light is on or off

One or more of those abstractions may be an over-simplification!

Re: Hint 2

Ed in Leaside

Is the bulb not like Elliot Ness?

;-)

alexy

By George, I believe you've got it!

Nicely obfuscated, too!

Answer

Ed in Leaside

There are three possible states for the bulb: off & cold, off & warm, or on.

Correct

alexy

One seldom thinks of lightbulbs as having a short-term memory!

Nice Job