>>> symbolic n;
>>> I1 := {[k,i] : 1 <= k < i <= n };
>>> I2 := {[k,i,j] : 1 <= k < i,j <= n };
>>> T1 := {[k,i] -> [i,k,1,0]};
>>> T2 := {[k,i,j] -> [i,j,0,k]};
>>> T1(I1);
{[i,k,1,0]: 1 <= k < i <= n}
>>> T2(I2);
{[i,j,0,k]: 1 <= k < i,j <= n}
>>> codegen T1:I1,T2:I2;
for(t1 = 2; t1 <= n; t1++) {
  for(t2 = 1; t2 <= n; t2++) {
    for(t4 = 1; t4 <= min(t1-1,t2-1); t4++) {
      s2(t4,t1,t2);
    }
    if (t2 <= t1-1) {
      s1(t2,t1);
    }
  }
}

>>> codegen 2 T1:I1,T2:I2;
for(t1 = 2; t1 <= n; t1++) {
  s1(1,t1);
  for(t2 = 2; t2 <= t1-1; t2++) {
    for(t4 = 1; t4 <= t2-1; t4++) {
      s2(t4,t1,t2);
    }
    s1(t2,t1);
  }
  for(t2 = t1; t2 <= n; t2++) {
    for(t4 = 1; t4 <= t1-1; t4++) {
      s2(t4,t1,t2);
    }
  }
}