define new constant of_real for class real_algebra_1;
define set Reals as range of_real;
add lemmas about of_real and Reals
Arith = FOL +
classes arith < term
consts "0" :: "'a::arith" ("0")
"1" :: "'a::arith" ("1")
"+" :: "['a::arith,'a] => 'a" (infixl 60)
end