INDEX 
(The numbers refer to pages) 
Absolute invariant, 51 
Alternants, 41 
Annihilators, 34, 39, 72 
Apolarity, 78-84 
Binary form, 14, 91 
Canonical form of cubic, 17 
quartic, 50 
ternary cubic, 28 
Concomitants, 93, 97 
Conic, 2, 21, 24, 94 
Contragredient, 94 
Contravariant, 94 
Convolution, 85 
Covariant, 12, 15, 66 
— in terms of roots, 56 
symbolic factors, 67, 95 
— as invariant, 71 
Cross-ratio, 5, 15, 56 
Cubic curves, 25-29, 81 
— form, 14, 16, 48, 80, 89, 93 
Degree, 30 
Differential operators, 36, 59, 95 
Discriminant of binary cubic, 17, 36 
quadratic, 10 
p-ic, 55 
ternary quadratic, 24 
Double point, 83 
Euler’s theorem, 15, 41 
Finiteness of covariants, 70-76 
syzygies, 76 
Forms, 14 
Functional determinant, 12 
Fundamental system, 48, 61, 84-91 
Harmonic, 15, 20, 78 
Hermite’s law of reciprocity, 45, 91 
Hessian, 11, 15-18, 23-28, 58, 66, 84, 93 
— curve, 25 
Hilbert’s theorem, 72 
Homogeneity, 14, 30, 37 
Homogeneous coordinates, 8, 20 
Identity transformation, 33 
Index, 10, 14, 15, 31, 32 
Inflexion point, 26-28, 82 
— tangent, 26, 82 
— triangle, 27 
Intermediate invariant, 19 
Interpretation of invariants, 2, 10, 23 
Invariant, 1, 10, 14, 28 
— in terms of roots, 54 
Inverse transformation, 33 
Irrational invariant, 55 
Irreducible covariant. 87 
Isobaric, 31, 32, 38, 42 
Jacobian. 12. 15, 18, 29. 65, 83, 93 
Leader of covariant, 40, 43, 58 
Line coordinates. 93, 97 
— equation of conic. 94 
Linear form, 9, 14, 33. 84 
— fractional transformation, 6, 22 
— transformation, 3, 9, 22. 33. 34, 
Mixed concomitant, 94, 97 
Order, 14 
Partitions, 44, 45 
Perspective, 4 
99