## E3atest.txt      check of P-Q pairs
#  if following X** =0, then the relation EPQE holds
with(DEtools):
read "equations.txt":
read "E3aPQ.txt":

e3apq:=proc(A,B,EE) 
         return(factor(mult(EE,A,[dx,x])-mult(B,E3a,[dx,x]))):  end proc:

X1p:=e3apq(P1p,Q1p,subs(e1=e1+1,E3a));
X1n:=e3apq(P1n,Q1n,subs(e1=e1-1,E3a));
X2p:=e3apq(P2p,Q2p,subs(e2=e2+1,E3a));
X2n:=e3apq(P2n,Q2n,subs(e2=e2-1,E3a));
X5p:=e3apq(P5p,Q5p,subs(e5=e5+2,E3a));
X5n:=e3apq(P5n,Q5n,subs(e5=e5-2,E3a));

X1p2p:=e3apq(P1p2p,Q1p2p,subs({e1=e1+1,e2=e2+1},E3a));
X1n2n:=e3apq(P1n2n,Q1n2n,subs({e1=e1-1,e2=e2-1},E3a));

X1p2p5n:=e3apq(P1p2p5n,Q1p2p5n,subs({e1=e1+1,e2=e2+1,e5=e5-2},E3a));
X1n2n5p:=e3apq(P1n2n5p,Q1n2n5p,subs({e1=e1-1,e2=e2-1,e5=e5+2},E3a));