Search found 33 matches

by jgf
Sun Sep 30, 2007 2:47 am UTC
Forum: Your art and links
Topic: Microbadge poll
Replies: 6
Views: 1908

Re: Microbadge poll

I'm modifying this poll. See here. Please post over there instead.

Thank you everyone who's voted.
by jgf
Sun Sep 30, 2007 2:44 am UTC
Forum: Your art and links
Topic: Microbadge poll
Replies: 6
Views: 1908

Microbadge poll the 2nd

This is follow-up to my previous poll . People seem to like choice 2 more than choice 1, and I thought of a few variations, though Randall's is still the heavy favorite. Sorry for polling twice. Last one, I promise. I'm making an xkcd microbadge for BGG . (A microbadge is an icon below your avatar u...
by jgf
Sat Sep 29, 2007 2:32 pm UTC
Forum: Your art and links
Topic: Microbadge poll
Replies: 6
Views: 1908

Microbadge poll

I'm making an xkcd microbadge for BGG . (A microbadge is an icon below your avatar used to display interests/ideas/professions/etc. you identify with. Hence displaying an xkcd microbadge shouts to the world you read xkcd.) Please vote which one I should submit: ⋅  http://www.eecs.berkeley....
by jgf
Thu Jun 14, 2007 5:57 pm UTC
Forum: Science
Topic: Glow-in-the-dark stars + surveying
Replies: 8
Views: 2292

Glow-in-the-dark stars + surveying

So my roommate and I have a project: We're going put glow-in-the-dark stars on our ceiling such that, if you stand in a particular spot, the ceiling of the living room will look like the night sky on epoch J2000.0. I've been busy scraping the SIMBAD astronomy database for the top N brightest stars v...
by jgf
Fri Oct 13, 2006 6:50 am UTC
Forum: Logic Puzzles
Topic: Baby dropping
Replies: 8
Views: 5093

I think this problem has already been posted here.

I'm guessing you want to minimize the worst case number of drops (and all drops take the same amount of time) rather than minimizing the expected number of drops.
by jgf
Thu Oct 12, 2006 11:44 pm UTC
Forum: Logic Puzzles
Topic: Pirate Democracy [Solution]
Replies: 27
Views: 11818

phlip's induction proof is the same as my own. My argument for why collusion will not is that they are pirates, and the problem statement implies that they will reneg on a deal if it benefits them. Thus if we start with the limiting case of 2 pirates, the pirate #100 knows that if it ever gets to th...
by jgf
Thu Oct 12, 2006 6:13 pm UTC
Forum: Logic Puzzles
Topic: Yet Another Hat Problem [Solution]
Replies: 20
Views: 8725

I like this elegant solution.
by jgf
Thu Oct 12, 2006 5:56 pm UTC
Forum: Logic Puzzles
Topic: Caterpillar along a bungee
Replies: 1
Views: 3492

phlip has started a solution thread.
by jgf
Thu Oct 12, 2006 5:55 pm UTC
Forum: Logic Puzzles
Topic: Caterpillar along a bungee [solution]
Replies: 15
Views: 6759

I arrived at the exact same solution: the problem reduces to a harmonic series, which increases without bound. Heck, in phlip's write-up, all it has to do is exceed 1. The quick and dirty explaination of how the harmonic series increases without bound: Let S[2^n] = 1/2 + 1/3 + 1/4 + 1/5 + 1/6 + 1/7 ...
by jgf
Wed Oct 11, 2006 10:29 pm UTC
Forum: Logic Puzzles
Topic: Sex problem
Replies: 35
Views: 15792

What rlo said. Yes, we all agree that the genders of two siblings are independent of each other. However, depending on how to interpret the statement, "You know one of them is a boy," it maps to one of two different events, which affects the answer. So stop arguing math and start arguing s...
by jgf
Wed Oct 11, 2006 10:19 pm UTC
Forum: Logic Puzzles
Topic: 5-point problem
Replies: 20
Views: 8319

Glad you guys enjoyed it. I came upon it trying to design a board for a game, go figure... :roll: Hats off to phlip for his solutions! His original 3-point solution was the one I thought of until I realized that placing the two inner points along a line parallel to an axis limited the distance to 0....
by jgf
Wed Oct 11, 2006 9:48 pm UTC
Forum: Logic Puzzles
Topic: Sum and Product Man
Replies: 27
Views: 15997

There is sufficient information in the problem statement as it is written, and both [2,100] and [3,100] cases have unique solutions that have been verified.
by jgf
Wed Oct 11, 2006 9:43 pm UTC
Forum: Logic Puzzles
Topic: The squares game
Replies: 22
Views: 8560

Still thinking. In the meantime, reference Elwyn Berlekamp.
by jgf
Thu Oct 05, 2006 9:41 am UTC
Forum: Logic Puzzles
Topic: 5-point problem
Replies: 20
Views: 8319

Is 4 really that simple... [ponders]? Yeah, guess so.

I wonder if anyone with experience in chemistry or crystal structures would have any insights on this problem.
by jgf
Thu Oct 05, 2006 7:59 am UTC
Forum: Logic Puzzles
Topic: 5-point problem
Replies: 20
Views: 8319

Yes, thanks for that clarification.
by jgf
Thu Oct 05, 2006 2:23 am UTC
Forum: Individual XKCD Comic Threads
Topic: 0085: "Paths"
Replies: 19
Views: 10974

0085: "Paths"

I didn't find a "Paths" thread, so pardon if this is a repeat. The rainy season has officially started in Berkeley, which has me wondering about a related efficiency problem every year: Assuming rain is falling at rate R with wind blowing such that it falls with incident angle Theta relati...
by jgf
Thu Oct 05, 2006 1:00 am UTC
Forum: Logic Puzzles
Topic: 5-point problem
Replies: 20
Views: 8319

5-point problem

Imagine a square world. Since it's square, we might as well give it a cartesian coordinate system: place the origin in the southwest corner, x-axis going to the east, y-axis going north, with (1,1) in the northeast corner. The world is also cyclic, meaning if you walk east from (1,y0), you'll reappe...
by jgf
Thu Oct 05, 2006 12:42 am UTC
Forum: Logic Puzzles
Topic: The Locker Puzzle
Replies: 5
Views: 9616

This is one of my favorite puzzles. Must have first heard it a dozen years ago, and it's getting to the point where I hear "A 1000 lockers/lightbulbs are in a row..." and the answer springs to my head. :)
by jgf
Tue Oct 03, 2006 9:27 pm UTC
Forum: Logic Puzzles
Topic: Sex problem
Replies: 35
Views: 15792

Yeah, there's a difference between: "A person has a dominant phenotype. What is the probability they are heterozygous?" And: "A person received a dominant allele from his mother. What is the probability the allele received from his father is recessive?" Assuming 1 dominant allele...
by jgf
Tue Oct 03, 2006 8:43 pm UTC
Forum: Logic Puzzles
Topic: Sex problem
Replies: 35
Views: 15792

Actually, I think it's closer to 66.7% :wink: The statement "The other child is a girl with 50% probability" does not follow from the given "A couple has at least one boy." Rather, it could follow from a statement like "A couple's younger child is a boy," "A couple...
by jgf
Sun Oct 01, 2006 8:42 am UTC
Forum: Logic Puzzles
Topic: 3-way duel
Replies: 25
Views: 12163

Sure. Unless you want to try doing the more general case and solve it in terms of the To Hit probabilities, which is what I'm working on.
by jgf
Sun Oct 01, 2006 12:00 am UTC
Forum: Logic Puzzles
Topic: 3-way duel
Replies: 25
Views: 12163

Yeah, I reasoned it through like this: a person only shoots in the air if they believe their position would improve by passing rather than shooting. And by improve I mean someone else is shot by the time it gets around to them. All three people cannot all pass because each individual decision is co...
by jgf
Sat Sep 30, 2006 8:40 am UTC
Forum: Logic Puzzles
Topic: 3-way duel
Replies: 25
Views: 12163

Seems likely that they each fire at the person who is the most threat to them. It didn't seem that hard to me, mainly because only the first round is in question; by the second round, either someone has won or two people are left firing at each other. Actually, as jwwells points out, the solution i...
by jgf
Sat Sep 30, 2006 7:20 am UTC
Forum: General
Topic: xkcd sighting
Replies: 3
Views: 3177

xkcd sighting

Dr. McNinja mentioned xkcd in its footnote: "Dukeicide is not a real word, and that's probably not a proper application of quantum theory. This is not xkcd."
by jgf
Sat Sep 30, 2006 3:01 am UTC
Forum: Logic Puzzles
Topic: 3-way duel
Replies: 25
Views: 12163

Good question. I've amended the problem statement: assume your opponents are perfectly logical and boring and will use a shooting strategy that maximizes their likelihood of survival.
by jgf
Sat Sep 30, 2006 1:41 am UTC
Forum: Logic Puzzles
Topic: 3-way duel
Replies: 25
Views: 12163

3-way duel

Here's a fun little problem I read in some book I've long forgotten: An argument over who gets the last slice of pi escalates out of hand and you find yourself in a 3-way duel. You have a 1/3 chance of hitting your target. One opponent, V, has a 2/3 change. The other opponent, W, always hits his mar...
by jgf
Sat Sep 30, 2006 1:02 am UTC
Forum: Your art and links
Topic: Stick figure comic
Replies: 7
Views: 7813

Thanks! Shy Guy, Shy Girl has not been updated for the reason you said: there's only so much you can do with it. I've been planning another comic (with real art) about ballroom dancing, grad students, and relationships; the three have more in common than you'd think. Of course, then I read xkcd, and...
by jgf
Fri Sep 29, 2006 6:23 pm UTC
Forum: Your art and links
Topic: Stick figure comic
Replies: 7
Views: 7813

It depends on what you mean by pose. If you look at the two major styles of competitive ballroom, Standard and Latin, both have a hold that is used for all their component dances (exceptions: Tango and Paso Doble) with minor differences. And the changes for Tango and Paso Doble are easy to gloss ove...
by jgf
Fri Sep 29, 2006 5:50 am UTC
Forum: Your art and links
Topic: Stick figure comic
Replies: 7
Views: 7813

Stick figure comic

I once made a comic using stick figures. Probably won't make sense unless you do ballroom dancing, though...
by jgf
Fri Sep 29, 2006 5:42 am UTC
Forum: Logic Puzzles
Topic: The Devil's Quarter Game
Replies: 87
Views: 39222

I like this puzzle. As my math teacher always said, "Symmetry is math for sexy." :wink:
by jgf
Fri Sep 29, 2006 5:40 am UTC
Forum: Logic Puzzles
Topic: Sum and Product Man [solution]
Replies: 0
Views: 3632

Sum and Product Man [solution]

The original problem statement: And oracle selects two natural numbers from the range [2,100]. He tells one man ('Sum') the sum of the two values and another man ('Product') the product of the two values. The men are asked to determine the original pair of numbers. Both men have perfect logic, know ...
by jgf
Thu Sep 28, 2006 9:57 am UTC
Forum: Logic Puzzles
Topic: Sum and Product Man
Replies: 27
Views: 15997

Assume the numbers were 2 and 6. Then Sum would be given 8. From this, he knows the numbers are either (2,6), (3,5), or (4,4). However, if the numbers were (3,5), he would know Product was told 15, and Product would then know the numbers. Therefore Product could not have 15 and Sum could not have 8....
by jgf
Tue Sep 26, 2006 9:23 pm UTC
Forum: Logic Puzzles
Topic: Weighing Marbles
Replies: 48
Views: 43755

Eureka!

Finally got the answer after several false starts. Yes, 41 coins is possible in 4 weighings if 1) You don't care whether it is heavier or lighter, just that it is counterfeit, and 2) You have one spare coin you know is not counterfeit. Each condition is worth 1 coin more you can differentiate. It sh...

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