It is useful to view computation as simulation,
* cf.*: * isomorphism of semigroups*.[Preparata, F. P. and
Yeh, R. T., * Introduction to Discrete Structures*, Addison-Wesley, 1973,
p. 129.]

Given two semigroupsGand_{1}= [S, °]G, an invertible function_{2}= [T, * ]&phi : S &rarr Tis said to be anisomorphismbetweenGand_{1}Gif, for every_{2}aandbinS,&phi (a ° b) = &phi (a) * &phi (b)

from which:
* a ° b = &phi ^{-1} ( &phi (a) * &phi (b) ) *

(princ-to-string (+ (read-from-string "2") (read-from-string "3"))) "5"