scheme :: CGAMES_1:sch 6
Func1RecEx{ F₁( ConwayGame, Function) -> set } :

for g being ConwayGame ex f being Function st
( dom f = the_Tree_of g & ( for g1 being ConwayGame st g1 in dom f holds
f . g1 = F₁(g1,(f | (the_proper_Tree_of g1))) ) )