# Omega Calculator v1.2 (based on Omega Library 1.2, August, 2000):
# symbolic n,m;
# 
# d11 := {[i,j] -> [i,2i+j] : 1 <= i <= n && 1 <= j,2i+j <= m};
# 
# d12 := {[i,j] -> [i,j+4] : 1 <= i <= n && 1 <= j,j+4 <= m};
# 
# d := d11 union d12;
# 
# e := d - (d+ compose d);
# 
# gist e given d;

{[i,j] -> [i,2i+j] : 1 <= i <= 3, n && 1 <= j && 2i+j <= m} union
 {[i,j] -> [i,2i+j] : Exists ( alpha : 2alpha = 1+i && 5 <= i <= n && 2i+j <= m && 1 <= j)} union
 {[i,j] -> [i,j+4] : 2 <= i <= n && 1 <= j <= m-4}

#