Non minimal order cross section  

Counter Example to [Fels Olver Theorem 13.3 (1999)] 

fr > Section:=[x=0,u[0]=0,v[0]=0,v[1]=0,v[2]=0, v[3]=1]:
 

fr > C , Invariantizations := dmf (LieAlg,Section, fr, [op(Section), u[1]=I1,v[4]=J4]):
 

"Section :" 

[v[3] = 1, v[2] = 0, v[1] = 0, v[0] = 0, u[0] = 0, x = 0] 

"Transversality condition :"   u[1]*u[2]
"Invariantizations:"
 

x = 0, u[0] = 0, v[0] = 0, v[1] = 0, v[2] = 0, v[3] = 1, u[1] = I1, v[4] = J4, u[2] = y1, u[3] = y2, u[4] = y3
x = 0, u[0] = 0, v[0] = 0, v[1] = 0, v[2] = 0, v[3] = 1, u[1] = I1, v[4] = J4, u[2] = y1, u[3] = y2, u[4] = y3
 

"Commutation rules" 

 

"Syzygies" 

[-3*y0[0]^3*I1[0]^6-3*y0[0]^3*I1[0]^4-4*y0[0]^3*I1[0]^4*y2[0]^2+3*y0[0]^2*I1[0]^3*y2[1]+4*y0[0]^2*I1[0]^3*J4[0]*y2[0]-3*y0[0]^2*I1[0]^3*y3[0]-3*y0[0]*I1[0]*y2[0]+3*J4[0], 7*y0[0]^2*I1[0]^3*y2[0]-4*y0[...
[-3*y0[0]^3*I1[0]^6-3*y0[0]^3*I1[0]^4-4*y0[0]^3*I1[0]^4*y2[0]^2+3*y0[0]^2*I1[0]^3*y2[1]+4*y0[0]^2*I1[0]^3*J4[0]*y2[0]-3*y0[0]^2*I1[0]^3*y3[0]-3*y0[0]*I1[0]*y2[0]+3*J4[0], 7*y0[0]^2*I1[0]^3*y2[0]-4*y0[...
[-3*y0[0]^3*I1[0]^6-3*y0[0]^3*I1[0]^4-4*y0[0]^3*I1[0]^4*y2[0]^2+3*y0[0]^2*I1[0]^3*y2[1]+4*y0[0]^2*I1[0]^3*J4[0]*y2[0]-3*y0[0]^2*I1[0]^3*y3[0]-3*y0[0]*I1[0]*y2[0]+3*J4[0], 7*y0[0]^2*I1[0]^3*y2[0]-4*y0[...
[-3*y0[0]^3*I1[0]^6-3*y0[0]^3*I1[0]^4-4*y0[0]^3*I1[0]^4*y2[0]^2+3*y0[0]^2*I1[0]^3*y2[1]+4*y0[0]^2*I1[0]^3*J4[0]*y2[0]-3*y0[0]^2*I1[0]^3*y3[0]-3*y0[0]*I1[0]*y2[0]+3*J4[0], 7*y0[0]^2*I1[0]^3*y2[0]-4*y0[...
[-3*y0[0]^3*I1[0]^6-3*y0[0]^3*I1[0]^4-4*y0[0]^3*I1[0]^4*y2[0]^2+3*y0[0]^2*I1[0]^3*y2[1]+4*y0[0]^2*I1[0]^3*J4[0]*y2[0]-3*y0[0]^2*I1[0]^3*y3[0]-3*y0[0]*I1[0]*y2[0]+3*J4[0], 7*y0[0]^2*I1[0]^3*y2[0]-4*y0[...
 

"Syzygies with attempt to eliminate the y's" 

y0[0] = 1/(I1[0]*y1[0]) 

y1[1] = y1[0]*(6*I1[1]*I1[0]-6*I1[0]*y1[0]+J4[0]*I1[0]^2+J4[0])/(I1[0]^2+1) 

y3[0] = (-1+2*I1[0]^2*y1[0]^2*J4[1]-6*y1[0]^3*I1[1]-I1[0]^6+y1[0]^2*J4[1]+3*y1[0]^4-3*I1[0]^4+3*y1[0]^2*I1[1]^2+5*I1[0]*y1[0]^2*J4[0]*I1[1]+y1[0]^2*J4[0]^2+I1[0]^4*y1[0]^2*J4[0]^2+2*y1[0]^2*J4[0]^2*I1...
y3[0] = (-1+2*I1[0]^2*y1[0]^2*J4[1]-6*y1[0]^3*I1[1]-I1[0]^6+y1[0]^2*J4[1]+3*y1[0]^4-3*I1[0]^4+3*y1[0]^2*I1[1]^2+5*I1[0]*y1[0]^2*J4[0]*I1[1]+y1[0]^2*J4[0]^2+I1[0]^4*y1[0]^2*J4[0]^2+2*y1[0]^2*J4[0]^2*I1...
y3[0] = (-1+2*I1[0]^2*y1[0]^2*J4[1]-6*y1[0]^3*I1[1]-I1[0]^6+y1[0]^2*J4[1]+3*y1[0]^4-3*I1[0]^4+3*y1[0]^2*I1[1]^2+5*I1[0]*y1[0]^2*J4[0]*I1[1]+y1[0]^2*J4[0]^2+I1[0]^4*y1[0]^2*J4[0]^2+2*y1[0]^2*J4[0]^2*I1...
y3[0] = (-1+2*I1[0]^2*y1[0]^2*J4[1]-6*y1[0]^3*I1[1]-I1[0]^6+y1[0]^2*J4[1]+3*y1[0]^4-3*I1[0]^4+3*y1[0]^2*I1[1]^2+5*I1[0]*y1[0]^2*J4[0]*I1[1]+y1[0]^2*J4[0]^2+I1[0]^4*y1[0]^2*J4[0]^2+2*y1[0]^2*J4[0]^2*I1...
y3[0] = (-1+2*I1[0]^2*y1[0]^2*J4[1]-6*y1[0]^3*I1[1]-I1[0]^6+y1[0]^2*J4[1]+3*y1[0]^4-3*I1[0]^4+3*y1[0]^2*I1[1]^2+5*I1[0]*y1[0]^2*J4[0]*I1[1]+y1[0]^2*J4[0]^2+I1[0]^4*y1[0]^2*J4[0]^2+2*y1[0]^2*J4[0]^2*I1...
 

y2[0] = y1[0]*(3*I1[1]*I1[0]+J4[0]+J4[0]*I1[0]^2-3*I1[0]*y1[0])/(I1[0]^2+1) 

fr > Invariantizations; rewrite_rules(C);
 

[x = 0, u[0] = 0, v[0] = 0, v[1] = 0, v[2] = 0, v[3] = 1, u[1] = I1[0], v[4] = J4[0], u[2] = y1[0], u[3] = y2[0], u[4] = y3[0], u[5] = 1/3*(3*y3[1]*I1[0]*y1[0]+10*y1[0]^2*J4[0]*y2[0]+5*y1[0]*J4[0]*I1[...
[x = 0, u[0] = 0, v[0] = 0, v[1] = 0, v[2] = 0, v[3] = 1, u[1] = I1[0], v[4] = J4[0], u[2] = y1[0], u[3] = y2[0], u[4] = y3[0], u[5] = 1/3*(3*y3[1]*I1[0]*y1[0]+10*y1[0]^2*J4[0]*y2[0]+5*y1[0]*J4[0]*I1[...
[x = 0, u[0] = 0, v[0] = 0, v[1] = 0, v[2] = 0, v[3] = 1, u[1] = I1[0], v[4] = J4[0], u[2] = y1[0], u[3] = y2[0], u[4] = y3[0], u[5] = 1/3*(3*y3[1]*I1[0]*y1[0]+10*y1[0]^2*J4[0]*y2[0]+5*y1[0]*J4[0]*I1[...
[x = 0, u[0] = 0, v[0] = 0, v[1] = 0, v[2] = 0, v[3] = 1, u[1] = I1[0], v[4] = J4[0], u[2] = y1[0], u[3] = y2[0], u[4] = y3[0], u[5] = 1/3*(3*y3[1]*I1[0]*y1[0]+10*y1[0]^2*J4[0]*y2[0]+5*y1[0]*J4[0]*I1[...
[x = 0, u[0] = 0, v[0] = 0, v[1] = 0, v[2] = 0, v[3] = 1, u[1] = I1[0], v[4] = J4[0], u[2] = y1[0], u[3] = y2[0], u[4] = y3[0], u[5] = 1/3*(3*y3[1]*I1[0]*y1[0]+10*y1[0]^2*J4[0]*y2[0]+5*y1[0]*J4[0]*I1[...
[x = 0, u[0] = 0, v[0] = 0, v[1] = 0, v[2] = 0, v[3] = 1, u[1] = I1[0], v[4] = J4[0], u[2] = y1[0], u[3] = y2[0], u[4] = y3[0], u[5] = 1/3*(3*y3[1]*I1[0]*y1[0]+10*y1[0]^2*J4[0]*y2[0]+5*y1[0]*J4[0]*I1[...
 

[[y0[0] = 1/(I1[0]*y1[0]), y1[1] = y1[0]*(6*I1[1]*I1[0]-6*I1[0]*y1[0]+J4[0]*I1[0]^2+J4[0])/(I1[0]^2+1), y3[0] = (-1+2*I1[0]^2*y1[0]^2*J4[1]-6*y1[0]^3*I1[1]-I1[0]^6+y1[0]^2*J4[1]+3*y1[0]^4-3*I1[0]^4+3*...
[[y0[0] = 1/(I1[0]*y1[0]), y1[1] = y1[0]*(6*I1[1]*I1[0]-6*I1[0]*y1[0]+J4[0]*I1[0]^2+J4[0])/(I1[0]^2+1), y3[0] = (-1+2*I1[0]^2*y1[0]^2*J4[1]-6*y1[0]^3*I1[1]-I1[0]^6+y1[0]^2*J4[1]+3*y1[0]^4-3*I1[0]^4+3*...
[[y0[0] = 1/(I1[0]*y1[0]), y1[1] = y1[0]*(6*I1[1]*I1[0]-6*I1[0]*y1[0]+J4[0]*I1[0]^2+J4[0])/(I1[0]^2+1), y3[0] = (-1+2*I1[0]^2*y1[0]^2*J4[1]-6*y1[0]^3*I1[1]-I1[0]^6+y1[0]^2*J4[1]+3*y1[0]^4-3*I1[0]^4+3*...
[[y0[0] = 1/(I1[0]*y1[0]), y1[1] = y1[0]*(6*I1[1]*I1[0]-6*I1[0]*y1[0]+J4[0]*I1[0]^2+J4[0])/(I1[0]^2+1), y3[0] = (-1+2*I1[0]^2*y1[0]^2*J4[1]-6*y1[0]^3*I1[1]-I1[0]^6+y1[0]^2*J4[1]+3*y1[0]^4-3*I1[0]^4+3*...
[[y0[0] = 1/(I1[0]*y1[0]), y1[1] = y1[0]*(6*I1[1]*I1[0]-6*I1[0]*y1[0]+J4[0]*I1[0]^2+J4[0])/(I1[0]^2+1), y3[0] = (-1+2*I1[0]^2*y1[0]^2*J4[1]-6*y1[0]^3*I1[1]-I1[0]^6+y1[0]^2*J4[1]+3*y1[0]^4-3*I1[0]^4+3*...
[[y0[0] = 1/(I1[0]*y1[0]), y1[1] = y1[0]*(6*I1[1]*I1[0]-6*I1[0]*y1[0]+J4[0]*I1[0]^2+J4[0])/(I1[0]^2+1), y3[0] = (-1+2*I1[0]^2*y1[0]^2*J4[1]-6*y1[0]^3*I1[1]-I1[0]^6+y1[0]^2*J4[1]+3*y1[0]^4-3*I1[0]^4+3*...
[[y0[0] = 1/(I1[0]*y1[0]), y1[1] = y1[0]*(6*I1[1]*I1[0]-6*I1[0]*y1[0]+J4[0]*I1[0]^2+J4[0])/(I1[0]^2+1), y3[0] = (-1+2*I1[0]^2*y1[0]^2*J4[1]-6*y1[0]^3*I1[1]-I1[0]^6+y1[0]^2*J4[1]+3*y1[0]^4-3*I1[0]^4+3*...