Ceptre

block : type.

on block block : pred.
on_table block : pred.
clear block : pred.
arm_holding block : pred.
arm_free : pred.

stage blocks = {
pickup_from_block
  : on X Y * clear X * arm_free -o clear Y * arm_holding X.

pickup_from_table
  : on_table X * clear X * arm_free -o arm_holding X.

put_on_block
  : arm_holding X * clear Y -o on X Y * clear X * arm_free.

put_on_table
  : arm_holding X -o on_table X * clear X * arm_free.

} #interactive blocks.

a : block.
b : block.
c : block.

context init =
{ on_table a, on_table b, on c a, clear c, clear b, arm_free }

#trace _ blocks init.