3,400 reputation
1037
bio website mathpuzzle.com
location Champaign, IL
age 51
visits member for 3 years, 7 months
seen 9 hours ago

I run the site mathpuzzle, and used to be the main advisor for the TV show Numb3rs. I've contributed extensively to MathWorld. Before that, I wrote the Math Games columns for the MAA. I am now the chief editor for the Wolfram Demonstrations Project. Of my own Demonstrations there, some of my favorites are: - Mrs. Perkins's Quilts - Tightly Packed Squares - Social Golfer Problem - The Circles Of Descartes - Triangle Calculator


Jan
13
awarded  Revival
Jan
13
answered $1^2+2^2+\cdots+24^2=70^2$ and squarily squaring the torus
Jan
13
revised Integer hexagonal grid variations for Harborth
added 2 characters in body
Jan
13
revised Integer hexagonal grid variations for Harborth
added 185 characters in body
Jan
13
asked Integer hexagonal grid variations for Harborth
Jan
9
answered Graph Theory book with lots of Named Graphs/ Graph Families
Oct
7
revised Can -9 to 9 be placed in 41 lines of zero?
Added exact values for more points.
Oct
7
revised Can -9 to 9 be placed in 41 lines of zero?
added 628 characters in body
Oct
7
comment Can -9 to 9 be placed in 41 lines of zero?
For a cubic curve, going through 2 rational points on a curve will go through a third. But I don't know why adding numbers to the lattice points allows for lots of consistent sums.
Oct
7
revised Can -9 to 9 be placed in 41 lines of zero?
Added links.
Oct
7
asked Can -9 to 9 be placed in 41 lines of zero?
Sep
30
awarded  Explainer
Sep
25
comment Shannon number upper and lower bounds
I wouldn't accept that number. First step -- calculate the number of possible pawn positions. For each position, have a minimum number of captures required to reach that position. Also, calculate which pieces are nonmobile in a given position. Second step -- for each pawn position, calculate the number of legal positions for the remaining mobile pieces. Not all positions will be reachable, but that doesn't matter for estimates. Exercise -- no pawns moved or captured. How many positions are possible?
Sep
11
awarded  Nice Question
Aug
26
asked Lattice worms with nontrivial deaths
Aug
15
revised Is there an aperiodic tiling consisting of deformed hexagons?
Added picture
Aug
15
comment For what integers $n$ is this divisibility statement true?
481 -- -32, -14, -11, -5, -3, -2, 0, 1, 4, 6, 30, 481 xxxxxx 1642 -- -41, -8, -5, -2, 0, 1, 3, 4, 10, 40, 1642 xxxxxx 1625 -- -58, -7, -4, -3, -1, 0, 2, 5, 8, 56, 1625 xxxxxx 707 -- -22, -19, -7, -4, -1, 0, 2, 3, 5, 14, 707 xxxxxx
Aug
15
comment Can 23 of this polycube fit in a 5x5x5 box?
Analyze fitting 8 into a 5x5x2 space. Fill all but one cube on the bottom layer. Corner=240 sols, middle edge=192 sols, center=70 sols. In many of those 502 solutions, the second layer has too many unfillable holes, but some are okay. Pick the good sets of voids, add them to a 5x5x3, and look at the 15 piece problem. Or find all good void sets for the 2nd and 4th layer, and do a bunch of 7 piece tests.
Aug
15
answered Is there an aperiodic tiling consisting of deformed hexagons?
Jul
24
answered Tricky (extremal?) combinatorics problem