nhaliday + puzzles   63

Best Topology Olympiad ***EVER*** - Affine Mess - Quora
Most people take courses in topology, algebraic topology, knot theory, differential topology and what have you without once doing anything with a finite topological space. There may have been some quirky questions about such spaces early on in a point-set topology course, but most of us come out of these courses thinking that finite topological spaces are either discrete or only useful as an exotic counterexample to some standard separation property. The mere idea of calculating the fundamental group for a 4-point space seems ludicrous.

Only it’s not. This is a genuine question, not a joke, and I find it both hilarious and super educational. DO IT!!
nibble  qra  announcement  math  geometry  topology  puzzles  rec-math  oly  links  math.AT  ground-up  finiteness  math.GN 
october 2017 by nhaliday
The Easiest Way to Memorize the Algorithms of Rubik's Cube: 7 Steps
Learn to solve the Rubik’s cube in no time by taking advantage of your visual memory. You’ve probably been playing with Rubik’s cube and wondering how to solve it. Eventually, you may have succeeded by following an online tutorial. While there are several methods to solve the 3x3 cube, these techniques usually consist of a number of algorithms that look something like this: T R Ti Ri Ti Fi T F.

Some people can memorize such sequences without difficulty. But what about the rest of us who are better at remembering peoples faces rather than their names? The good news is that the algorithms can be converted into easy to memorize graphics so that you don’t need to spend days learning the sequences by heart!
diy  puzzles  visuo  spatial  explanation  howto  math.GR  rec-math  wordlessness 
july 2017 by nhaliday
reference request - The coupon collector's earworm - MathOverflow
I have a playlist with, say, N pieces of music. While using the shuffle option (each such piece is played randomly at each step), I realized that, generally speaking, I have to hear quite a lot of times the same piece before the last one appears. It makes me think of the following question:

At the moment the last non already heard piece is played, what is the max, in average, of number of times the same piece has already been played?

A: e log N + o(log N)
q-n-a  overflow  math  math.CO  tidbits  puzzles  probability  magnitude  oly  nibble  concentration-of-measure  binomial 
january 2017 by nhaliday
pr.probability - Google question: In a country in which people only want boys - MathOverflow
- limits to 1/2 w/ number of families -> ∞
- proportion of girls in one family is biased estimator of proportion in general population (larger families w/ more girls count more)
- interesting comment on Douglas Zare's answer (whether process has stopped or not)
puzzles  math  google  thinking  probability  q-n-a  gotchas  tidbits  math.CO  overflow  nibble  paradox  gender  bias-variance  stochastic-processes 
december 2016 by nhaliday
Low-hanging fruit | West Hunter
Think about it: peptic and duodenal ulcer were fairly common, and so were effective antibiotics, starting in the mid-40s. . Every internist in the world – every surgeon – every GP was accidentally curing ulcers – not just one or twice, but again and again. For decades. Almost none of them noticed it, even though it was happening over and over, right in front of their eyes. Those who did notice were ignored until the mid-80s, when Robin Warren and Barry Marshall finally made the discovery stick. Even then, it took something like 10 years for antibiotic treatment of ulcers to become common, even though it was cheap and effective. Or perhaps because it was cheap and effective.

This illustrates an important point: doctors are lousy scientists, lousy researchers. They’re memorizers, not puzzle solvers. Considering that Western medicine was an ineffective pseudoscience – actually, closer to a malignant pseudoscience – for its first two thousand years, we shouldn’t be surprised. Since we’re looking for low-hanging fruit, this is good news. It means that the great discoveries in medicine are probably not mined out. From our point of view, past incompetence predicts future progress. The worse, the better!
stagnation  science  history  medicine  innovation  technology  west-hunter  low-hanging  meta:medicine  the-world-is-just-atoms  🔬  scitariat  info-dynamics  bounded-cognition  error  chart  econotariat  marginal-rev  being-right  ideas  discovery  the-trenches  s:*  alt-inst  ability-competence  cost-benefit  track-record  problem-solving  puzzles 
november 2016 by nhaliday
Olimpiada Informatyczna
old link seems broken?: http://main.edu.pl/en/archive/oi

Polish Informatics Olympiad, known for very difficult problems
database  problem-solving  puzzles  eastern-europe  oly  usaco-ioi  oly-programming  unit  multi  quixotic 
april 2016 by nhaliday

bundles : academegrowth

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