Preface ........................................................ xi
1 Polarity ..................................................... 1
1.1 Polar hypersurfaces ..................................... 1
1.2 The dual hypersurface .................................. 28
1.3 Polar s-hedra .......................................... 35
1.4 Dual homogeneous forms ................................. 48
1.5 First examples ......................................... 60
Exercises ................................................... 64
Historical notes ............................................ 66
2 Conies and quadric surfaces ................................. 69
2.1 Self-polar triangles ................................... 69
2.2 Poncelet relation ...................................... 81
2.3 Quadric surfaces ....................................... 91
Exercises .................................................. 108
Historical notes ........................................... 111
3 Plane cubics ............................................... 114
3.1 Equations ............................................. 114
3.2 Polars of a plane cubic ............................... 124
3.3 Projective generation of cubic curves ................. 133
3.4 Invariant theory of plane cubics ...................... 136
Exercises .................................................. 141
Historical notes ........................................... 143
4 Determinantal equations .................................... 146
4.1 Plane curves .......................................... 146
4.2 Determinantal equations for hypersurfaces ............. 160
Exercises .................................................. 184
Historical notes ........................................... 186
5 Theta characteristics ...................................... 188
5.1 Odd and even theta characteristics .................... 188
5.2 Hyperelliptic curves .................................. 192
5.3 Theta functions ....................................... 197
5.4 Odd theta characteristics ............................. 204
5.5 Scorza correspondence ................................. 212
Exercises .................................................. 224
Historical notes ........................................... 224
6 Plane quartics ............................................. 226
6.1 Bitangents ............................................ 226
6.2 Determinant equations of a plane quartic .............. 235
6.3 Even theta characteristics ............................ 243
6.4 Invariant theory of plane quartics .................... 265
6.5 Automorphisms of plane quartic curves ................. 266
Exercises .................................................. 276
Historical notes ........................................... 278
7 Cremona transformations .................................... 280
7.1 Homaloidal linear systems ............................. 280
7.2 First examples ........................................ 294
7.3 Planar Cremona transformations ........................ 303
7.4 Elementary transformations ............................ 320
7.5 Noether's Factorization Theorem ....................... 329
Exercises .................................................. 342
Historical notes ........................................... 344
8 del Pezzo surfaces ......................................... 347
8.1 First properties ...................................... 347
8.2 The Etf-lattice ....................................... 358
8.3 Anticanonical models .................................. 379
8.4 del Pezzo surfaces of degree ≥ 6 ...................... 386
8.5 del Pezzo surfaces of degree 5 ........................ 389
8.6 Quartic del Pezzo surfaces ............................ 396
8.7 del Pezzo surfaces of degree 2 ........................ 405
8.8 del Pezzo surfaces of degree 1 ........................ 411
Exercises .................................................. 422
Historical notes ........................................... 423
9 Cubic surfaces ............................................. 426
9.1 Lines on a nonsingular cubic surface .................. 426
9.2 Singularities ......................................... 443
9.3 Determinantal equations ............................... 449
9.4 Representations as sums of cubes ...................... 459
9.5 Automorphisms of cubic surfaces ....................... 483
Exercises .................................................. 502
Historical notes .............................................. 504
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