A:
You want to hear a joke I wrote?
B:
No. Nobody writes jokes.
A:
This is my first! Here it goes: What's the difference between how Republicans and Democrats relate to homosexuals?
B:
There's a million differences. This is why I hate jokes, they
A:
Nope! Republicans accuse people they don't like of being homosexuals, while Democrats accuse people they don't like of being CLOSETED homosexuals!
B:
See. This is another reason why I hate jokes, that's a huge over-simplification.
A:
Well, yeah. But not any more than in other jokes.
B:
Ok. Are we done?
A:
Nope! I wrote a riddle, too!
B:
Brilliant.
A:
Ok, so imagine you go to the gym every Monday, Wednesday, and Friday, at 2 p.m. And you always see this other guy there, so there's two possibilities, right? Either he ALSO goes every week at the same time on Monday, Wednesday, and Friday, or he actually goes EVERY DAY, at 2 p.m., and you only see him on Monday, Wednesday, and Friday.
B:
Or he goes every Monday, Tuesday, Wednesday, and Friday. Or he goes every Monday, Wednesday, Thursday, and Friday. Or he flips a coin every day at 2 p.m. to see whether he should go or not, and so far, it has come up heads at least every Monday, Wednesday, or Friday. Or
A:
Well, ignore those other possibilities for now. I'll work on the language to constrain it more. Regardless, you are trying to figure out whether he goes EVERY day, or only on the days you go.
B:
I don't care how often he goes.
A:
Just assume you do. Are riddles supposed to motivate the problem, too?
B:
I think riddles primarily appeal to people who don't respond to the types of problems that motivate most people.
A:
Well, assume you want to know. But. BUT! You also know that he is very vain, and will tell you that he goes to the gym everyday, regardless of whether it's true or not! SO. How do you find out how often he goes to the gym?
B:
I don't know, go on a Tuesday and see if he's there?
A:
Sorry, I forgot to mention, you aren't allowed to do anything besides talk to him. So you have to talk with him, or ask him something, to figure out how often he goes.
B:
What a bizarre constraint.
A:
Do you give up?
B:
Yes.
A:
You ask him often HE thinks that YOU go to the gym! If he says, "Monday, Wednesday, Friday", then it's clear that he goes every day, and sees negative examples of you visiting the gym! If he says he doesn't know, then he has only seen positive examples but recognizes his own imperfect sampling, and therefore only goes every Monday, Wednesday, and Friday!
B:
Yeah, or he just doesn't pay attention to whether you're there or not. He's not a weirdo like you. He's not a creep that stalks people at the gym and writes busted riddles about them.
A:
That's
B:
Or, you know. He could still go every Monday, Wednesday, Thursday, and Friday, and doesn't know what you do on Tuesdays.
A:
We already decided that the only two options are Monday, Wednesday, Friday or every weekday! Take that as writ!
B:
Wait, did the 2 p.m. part factor into the riddle at all?
A:
Nope! Looks like you got bit by a big old RED HERRING! Fooled ya!