Day 15 in Mat115

Today:

• Return 3.1 problems

• Sorry, I don't have 3.2 problems graded yet

• Collect problems 3.3.

• Questions/Comments on old stuff?

• Section 4.4:
  • What do we mean by symmetry?

  • Faces are not symmetric, in general

  • Rigid symmetries

  • A pattern in the plane is scalable (or has symmetry of scale) if the tiles that make up the pattern can be grouped into super-tiles that still cover the plane, and, if scaled down, coincide with the original pattern.

  • Tiling with pentagons

  • The Pinwheel Pattern

  • Penrose and toilet paper
• Links:
  • Tilings, Diffraction, and Quasicrystals
  • Tiling software