# Xah Math Blog Archive 2015-05 to 2015-05

### The Stanford Encyclopedia of Philosophy

The Stanford Encyclopedia of Philosophy is a great thing. A different take than Wikipedia.

### magic polyhedron

the Rubik cube of today have advanced. Now, there's stickerless versions, and better mechanical design.

see updated Magic Polyhedrons

### ℭ = Cardinality of the continuum.

ℚ = be rational, ℝ = get real.

ℭ = Cardinality of the continuum.

### Tiling and Patterns, Classic Text Now in Print Again

just discovered, this classic, definitive, book on tilings and patterns is in print again, now reprinted by Dover.

see also: Reading Notes on Tilings and Patterns

### tiling the plane with 5-fold symmetry tiles

John Baez, gave a intro on the problem of tiling the plane with 5-fold symmetry tiles At https://plus.google.com/117663015413546257905/posts/5CHdeLRckRm

see also [• The trouble with five By Craig Kaplan. At https://plus.maths.org/content/trouble-five , Accessed on 2015-05-11 ]

sample of tiling and patterns, see:

See also: Discontinuous Groups of Rotation and Translation in the Plane

### Skew But Fair Dice

it supposed to be fair dice. Am thinking there's a major difference from the cube. This one, has 2 different sides, like a coin. In a sense, when you throw this dice, it decides which of the side will fall first, then, decide which of the 3 faces will land.

So, one can actually make a 3-sided pyramid, and have 2 of them and glue the bottom together. So, we could make a infinite shape of 6 faced dice that's still fair. Then, if we wiggle the cutting plane like a saw tooth, we could create quite a lot strange looking and still fair 6-faced dice.

comment at https://plus.google.com/+XahLee/posts/L9FP178N6eq

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