Recent content by asmani

Oh I see what you mean. Let me clarify: It's a bijection from Q+ to W, and then from W to N, where W is the set of all 2m3n for all coprime n and m. Here is the bijection from W to N: Map the smallest member of W to 1, the second smallest member of W to 2, and so on

Can you give a counterexample?

I was thinking about bijection from Q to N. here is what I came up with: m/n --> 2m3n And it's easy to show there's a bijection from the set "2m3n for all coprime n and m" to N. Edit: This is Q+ to N. Does it work?

https://math.stackexchange.com/questions/1160411/is-there-a-one-to-one-function-from-the-natural-numbers-to-the-primes

What's the problem with this trivial solution: n --> n'th prime.

I understand what you mean by many answers. That's a nice pattern, thanks!

I found this, but it's not very nice: Each element of the first row is some reflection of the union of the other two in its column. So here is the answer:

Oh, did you mean the answer to "?" is all black? Well, that doesn't need a picture.

I'm sorry, that was bad English. I meant "Make a picture of the answer". Can you give a hint on what type of operation? I've tried unions, intersections, symmetric differences, shifts, reflections, rotations, reversing, and some combinations of these operations, none of them worked. should I...

Could you please illustrate your answer?

Dear moderator, if the thread is irrelevant to this forum section, please move it to the right section. Thanks.

Hey we have an infinite number of hats...

Yeah, sorry I accidentally omitted the "l" in "html".

This is an interesting riddle from here: http://www.brand.site.co.il/riddles/201607q.htm I'm having difficulty understanding the problem. If each hat is black/white with 50-50 probability, independent of the colors of other hats, then the probability of winning for n=2 is always 1/4, no matter...

Hi. As you can see in the video attached, the image of the street is projected on the ceiling! Only a window glass and a simple curtain is involved. How does this happen? And how can I optimize (the window angle curtain etc) to get the most clear picture?