Obstacles and Reversibility

[Colin Fiat]

Hello, glad to be a part of this forum.

After experimenting with bounded binary patterns, primarily polarity/parity based,
I came to question whether any pattern was reversible and to what extent; how many
generations. Testing this with various programs, scrips, and pencil/papers, I found
rudimentary methods. Tests using Golly proved successful. (.rle file attached - one
generation)

Aside from the above curiosity, I am also interested in fixed 'objects' which interfere
with each generation. Can Golly do this? Is there a program available which will allow
me to define custom CA rules and place fixed cells on the world grid?