NOTE ON THE STANDARD SOLUTIONS
20
[800
where the * denotes a value which is not in general = 0, but which may in any
particular case happen to be so.
For instance, let it be required for the binary quartic (a, b, c, d, e§cc, yY, to find
the asyzygetic seminvariants of the degree 4 and weight 6. Assuming for the
seminvariant the value in the left-hand column of the diagram, the unknown coefficients
being A, B, C, jD, E, F, G, this must be reduced to zero by the operation
ctdi•) + 2 bd c + 3cdd + 4dd e 5
and we thus obtain as many equations as there are terms of the degree 4 and
weight 5, as appearing by the second column
cidb + 2b?) c + 3 cdd -f- 4 dd e
A arc e
a 2 b e
2(7 + 2A
B „ d 2
„cd
D + 6B + 4A
C a b 2 e
a b' 2 d
SF -f 2D + 4(7
D „ bed
»be 2
2G+6E + SD
E „ c 3
a°b 3 c
4<G + SF
F a°b 3 d
G „ b 2 c 2
viz. the equations are
A
B
G
D E
F
G
2
+ 2
= 0,
4 +
6
+ 1
= 0,
4
+ 2
+ 3
= 0,
3 + 6
+ 2
= 0,
3
+ 4
= 0.
We have first a solution beginning B= 1, and secondly a solution beginning A — 1, with
B = 0: the resulting two seminvariants, say P and Q, are
F =
Q =
I
II
A
a 2 ce
0
1
1
1
B
,,d 2
1
o
-1
o
G
a b 2 e
0
-1
-1
- 1
D
„ bed
- 6
- 4
+ 2
- 4
E
,,c 3
+ 4
3 !
- 1
+ 3
F
a°b 3 d
+ 4
4 !
+ 4
G
„ b 2 c 2
- 3
- 31
+ 3