reserve R for Ring,
  r for Element of R,
  a, b, d1, d2 for Data-Location of R,
  il, i1, i2 for Nat,
  I for Instruction of SCM R,
  s,s1, s2 for State of SCM R,
  T for InsType of the InstructionsF of SCM R,
  k for Nat;

theorem Th14:
  InsCode I = 3 implies ex a, b st I = SubFrom(a,b)
proof
A1: I = [0,{},{}] or (ex a,b st I = a:=b) or (ex a,b st I = AddTo(a,b)) or (ex
  a,b st I = SubFrom(a,b)) or (ex a,b st I = MultBy(a,b)) or
  (ex i1 st I = goto(i1,R)) or
   (ex a,i1 st I = a=0_goto i1) or ex a,r st I = a:=r by SCMRING2:7;
  assume InsCode I = 3;
  hence thesis by A1;
end;
