README.md

Verified compilation into Conway's Game of Life

The following inspired this work:

• Nicolas Loizeau: https://www.nicolasloizeau.com/gol-computer and https://www.youtube.com/watch?v=Kk2MH9O4pXY&t=930

• Nicholas Carlini: https://nicholas.carlini.com/writing/2021/improved-logic-gates-game-of-life.html

To build the project:

• Install HOL
• Run Holmake from the project directory

Points of interest:

• gol_rulesScript.sml has the definition of the GOL next-state function step

• gol_in_gol_circuitScript.sml has the main theorem gol_in_gol_circuit_thm

• The gate designs are in gates/, in RLE format (which is supported by Golly - useful if you want to play with the gates outside the context of this formalization)

• The mega-cell design is in gol_in_gol_paramsLib.sml, as an ASCII art diagram that is parsed and verified in gol_in_gol_circuitScript.sml.

It should take about 2-5 minutes to compile the project.

Some pretty pictures that couldn't all fit in the paper

• The mega-cell:

• Propagation of values through the mega-cell:

• Symbolic evaluation of an AND gate:

• Symbolic evaluation of a crossover:

• Symbolic evaluation of a half-adder:

• Composition of gates:

• Spaceship evolution:

The tools for creating these images are in gol_svgScript.sml, so you can modify them to e.g. see images of the rest of the gates or show other patterns, etc.

There is also a simulator at ts/gol.html which you can use to see the symbolic computation in action. Hover over the pixels to see the values assigned at each point.