% A.I.Davydychev and A.G.Grozin, hep-ph/0102???
% Case q2=0

input_case nil$

% V(1,1,0) = I
% V(1,0,1) = I1

% Gamma(x+n)/Gamma(x)
procedure G(x,n);
if n>0 then for i:=0:(n-1) product (x+i)
else if n<0 then 1/(for i:=1:(-n) product (x-i))
else 1$

procedure V(n0,n1,n2);
if n0<=0 or max(n1,n2)<=0 then 0
else if n1=0 then
    (G(-d+3,n0+2*n2-3)*G(d/2-1,1-n2))/(factorial(n0-1)*factorial(n2-1))
    /((-4)^(n2-1)*w1^(n0+2*n2-3))*I1
else if n2=0 then
    (G(-d+3,n0+2*n1-3)*G(d/2-1,1-n1))/(factorial(n0-1)*factorial(n1-1))
    /((-4)^(n1-1)*w^(n0+2*n1-3))*I
else if n0>1 then % 0- (0)
    (n1*(w*V(n0-1,n1+1,n2)-V(n0-2,n1+1,n2))+n2*(w1*V(n0-1,n1,n2+1)-V(n0-2,n1,n2+1)))*2/(n0-1)
% n0=1
else if n2<0 then
    sub(w=w1,w1=w,I=I1,I1=I,V(1,n2,n1))
else if n2>1 then % 1+ 2- (2)
    (((d-2*n1-n2-2)*w1-(d-n1-2*n2)*w)*V(1,n1+1,n2-1)+(n1+1)*w*V(1,n1+2,n2-2))/((n2-1)*w1)
% n0=n2=1
else if n1>0 then % 1- (3)
    (-(d-n1-2)*V(1,n1-1,1)+(n1-1)*V(1,n1,0)-2*n1*w*w1*V(1,n1+1,0))/(2*(d-2*n1-2)*w1*(w1-w))
else % (3)
    (-2*(d-2*n1-4)*w1*(w1-w)*V(1,n1+1,1)+n1*V(1,n1+1,0)-2*(n1+1)*w*w1*V(1,n1+2,0))/(d-n1-3)$

remember V;

end;

% (0) n0 0+ + 2 n1 1+ (0- - w) + 2 n2 2+ (0- - w') = 0
procedure T0(n0,n1,n2);
n0*V(n0+1,n1,n2)
+2*n1*(V(n0-1,n1+1,n2)-w*V(n0,n1+1,n2))
+2*n2*(V(n0-1,n1,n2+1)-w1*V(n0,n1,n2+1))$

% (1) d-n0-n2-2n1 + w n0 0+ - n2 2+ 1- = 0
procedure T1(n0,n1,n2);
(d-n0-n2-2*n1)*V(n0,n1,n2)+w*n0*V(n0+1,n1,n2)-n2*V(n0,n1-1,n2+1)$

% (1') d-n0-n1-2n2 + w1 n0 0+ - n1 1+ 2- = 0
procedure T2(n0,n1,n2);
(d-n0-n1-2*n2)*V(n0,n1,n2)+w1*n0*V(n0+1,n1,n2)-n1*V(n0,n1+1,n2-1)$

procedure TT(n0,n1,n2);
V(n0,n1,n2)-sub(w=w1,w1=w,I=I1,I1=I,V(n0,n2,n1))$

% (2): w1 (1) - w (1')
% (d-n0-n1-n2)(w1-w) - n1 w1 + n2 w + w n1 1+ 2- - w1 n2 2+ 1- = 0
%
% (3): (1') - w1 (0) + 2 w1 1+ (2)
% d-n0-n1-2n2 + 2 w1 [(w1-w)(d-n0-n2-2n1-1) + n2 w - w1] 1+
%     - 2 w1 (n1 1+ + n2 2+) 0- - n1 1+ 2- + 2 w w1 (n1+1) 1++ 2- = 0

m:=3$

for n0:=-m:m do for n1:=-m:m do for n2:=-m:m do
if TT(n0,n1,n2) neq 0 then <<write n0,n1,n2; rederr "TT";>>;

for n0:=-m:m do for n1:=-m:m do for n2:=-m:m do
if T0(n0,n1,n2) neq 0 then <<write n0,n1,n2; rederr "T0";>>;

for n0:=-m:m do for n1:=-m:m do for n2:=-m:m do
if T1(n0,n1,n2) neq 0 then <<write n0,n1,n2; rederr "T1";>>;

for n0:=-m:m do for n1:=-m:m do for n2:=-m:m do
if T2(n0,n1,n2) neq 0 then <<write n0,n1,n2; rederr "T2";>>;

end;