Preface |
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vii | |
Acknowledgments |
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ix | |
Using This Book |
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xi | |
Part I: Examples of Varieties and Maps |
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Affine and Projective Varieties |
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3 | (14) |
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3 | (1) |
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Affine Space and Affine Varieties |
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3 | (1) |
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Projective Space and Projective Varieties |
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3 | (13) |
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5 | (1) |
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6 | (2) |
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8 | (1) |
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Analytic Subvarieties and Submanifolds |
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8 | (1) |
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9 | (1) |
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10 | (1) |
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Determinantal Representation of the Rational Normal Curve |
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11 | (1) |
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Another Parametrization of the Rational Normal Curve |
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11 | (1) |
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The Family of Plane Conics |
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12 | (1) |
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A Synthetic Construction of the Rational Normal Curve |
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13 | (1) |
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14 | (2) |
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Varieties Defined over Subfields of K |
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16 | (1) |
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A Note on Dimension, Smoothness, and Degree |
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16 | (1) |
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Regular Functions and Maps |
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17 | (15) |
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17 | (1) |
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Regular Functions on an Affine Variety |
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18 | (2) |
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20 | (1) |
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21 | (11) |
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23 | (1) |
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Determinantal Representation of Veronese Varieties |
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24 | (1) |
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Subvarieties of Veronese Varieties |
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24 | (1) |
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25 | (2) |
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Subvarieties of Segre Varieties |
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27 | (1) |
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28 | (1) |
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29 | (1) |
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30 | (1) |
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Combinations of Veronese and Segre Maps |
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30 | (2) |
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Cones, Projections, and More About Products |
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32 | (9) |
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32 | (1) |
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33 | (1) |
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34 | (3) |
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37 | (1) |
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38 | (1) |
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39 | (2) |
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Families and Parameter Spaces |
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41 | (7) |
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41 | (1) |
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42 | (1) |
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The Universal Hyperplane Section |
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43 | (1) |
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Parameter Spaces of Hypersurfaces |
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44 | (1) |
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Universal Families of Hypersurfaces |
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45 | (2) |
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47 | (1) |
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Ideals of Varieties, Irreducible Decomposition, and the Nullstellensatz |
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48 | (15) |
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48 | (2) |
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Ideals of Projective Varieties |
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50 | (1) |
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Irreducible Varieties and Irreducible Decomposition |
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51 | (2) |
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53 | (4) |
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54 | (1) |
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55 | (1) |
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56 | (1) |
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57 | (3) |
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Restatements and Corollaries |
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60 | (3) |
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Grassmannians and Related Varieties |
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63 | (9) |
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63 | (3) |
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Subvarieties of Grassmannians |
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66 | (6) |
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67 | (1) |
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An Analog of the Veronese Map |
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68 | (1) |
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Incidence Correspondences |
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68 | (1) |
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Varieties of Incident Planes |
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69 | (1) |
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The Join of Two Varieties |
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70 | (1) |
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70 | (2) |
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Rational Functions and Rational Maps |
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72 | (16) |
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72 | (1) |
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73 | (2) |
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75 | (2) |
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77 | (2) |
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78 | (1) |
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79 | (1) |
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79 | (1) |
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80 | (7) |
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81 | (1) |
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82 | (2) |
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The Quadric Surface Again |
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84 | (1) |
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85 | (2) |
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87 | (1) |
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88 | (10) |
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The Join of Two Varieties |
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88 | (1) |
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89 | (1) |
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90 | (1) |
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90 | (1) |
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Joins of Corresponding Points |
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91 | (1) |
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92 | (1) |
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Higher-Dimensional Scrolls |
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93 | (1) |
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More Incidence Correspondences |
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94 | (1) |
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95 | (1) |
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More Joins and Intersections |
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95 | (1) |
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96 | (1) |
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Rational Normal Scrolls II |
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97 | (1) |
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98 | (16) |
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Generic Determinantal Varieties |
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98 | (1) |
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98 | (1) |
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Secant Varieties of Segre Varieties |
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99 | (1) |
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Linear Determinantal Varieties in General |
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99 | (12) |
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100 | (3) |
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Secant Varieties to Rational Normal Curves |
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103 | (2) |
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Rational Normal Scrolls III |
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105 | (4) |
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Rational Normal Scrolls IV |
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109 | (2) |
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More General Determinantal Varieties |
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111 | (1) |
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Symmetric and Skew-Symmetric Determinantal Varieties |
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112 | (2) |
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Fano Varieties of Determinantal Varieties |
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112 | (2) |
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114 | (19) |
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The General Linear Group GLnK |
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114 | (1) |
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The Orthogonal Group SOnK |
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115 | (1) |
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The Symplectic Group Sp2nK |
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116 | (1) |
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116 | (7) |
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116 | (1) |
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117 | (1) |
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118 | (1) |
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119 | (1) |
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120 | (1) |
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121 | (1) |
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POnK Acts on Pn-1 (automorphisms of the Grassmannian) |
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122 | (1) |
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122 | (1) |
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123 | (1) |
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Quotients of Affine Varieties by Finite Groups |
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124 | (2) |
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Quotients of Affine Space |
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125 | (1) |
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126 | (1) |
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Quotients of Projective Varieties by Finite Groups |
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126 | (7) |
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Weighted Projective Spaces |
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127 | (6) |
Part II: Attributes of Varieties |
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Definitions of Dimension and Elementary Examples |
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133 | (18) |
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136 | (1) |
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136 | (2) |
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138 | (13) |
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142 | (1) |
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Varieties of Incident Planes |
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142 | (1) |
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143 | (3) |
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Secant Varieties in General |
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146 | (2) |
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148 | (1) |
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148 | (1) |
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(Some) Schubert Varieties |
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149 | (2) |
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More Dimension Computations |
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151 | (12) |
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151 | (1) |
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152 | (3) |
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Parameter Spaces of Twisted Cubics |
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155 | (6) |
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155 | (1) |
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Twisted Cubics on a General Surface |
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156 | (1) |
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157 | (1) |
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Curves of Type (a, b) on a Quadric |
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158 | (1) |
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159 | (2) |
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161 | (2) |
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GL(V) Acts on SymdV and kV |
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161 | (1) |
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PGLn+1K Acts on (Pn)1 and G(k, n)1 |
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161 | (2) |
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163 | (11) |
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Hilbert Functions and Polynomials |
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163 | (5) |
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Hilbert Function of the Rational Normal Curve |
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166 | (1) |
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Hilbert Function of the Veronese Variety |
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166 | (1) |
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Hilbert Polynomials of Curves |
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166 | (2) |
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168 | (6) |
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170 | (1) |
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171 | (1) |
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Complete Intersections: Koszul Complexes |
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172 | (2) |
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Smoothness and Tangent Spaces |
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174 | (12) |
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The Zariski Tangent Space to a Variety |
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174 | (3) |
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A Local Criterion for Isomorphism |
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177 | (4) |
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Projective Tangent Spaces |
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181 | (3) |
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184 | (2) |
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Gauss Maps, Tangential and Dual Varieties |
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186 | (14) |
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A Note About Characteristic |
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186 | (14) |
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188 | (1) |
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189 | (1) |
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The Variety of Tangent Lines |
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190 | (3) |
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Joins of Intersecting Varieties |
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193 | (2) |
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The Locus of Bitangent Lines |
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195 | (1) |
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196 | (4) |
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Tangent Spaces to Grassmannians |
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200 | (11) |
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Tangent Spaces to Grassmannians |
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200 | (2) |
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Tangent Spaces to Incidence Correspondences |
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202 | (1) |
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Varieties of Incident Planes |
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203 | (1) |
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The Variety of Secant Lines |
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204 | (1) |
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Varieties Swept out by Linear Spaces |
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204 | (2) |
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The Resolution of the Generic Determinantal Variety |
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206 | (2) |
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Tangent Spaces to Dual Varieties |
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208 | (1) |
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Tangent Spaces to Fano Varieties |
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209 | (2) |
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Further Topics Involving Smoothness and Tangent Spaces |
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211 | (13) |
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211 | (2) |
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Osculating Planes and Associated Maps |
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213 | (1) |
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The Second Fundamental Form |
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214 | (1) |
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The Locus of Tangent Lines to a Variety |
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215 | (1) |
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216 | (3) |
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Blow-ups, Nash Blow-ups, and the Resolution of Singularities |
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219 | (3) |
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Subadditivity of Codimensions of Intersections |
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222 | (2) |
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224 | (15) |
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227 | (4) |
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The Rational Normal Curves |
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229 | (2) |
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231 | (8) |
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231 | (2) |
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233 | (1) |
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Degrees of Cones and Projections |
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234 | (1) |
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235 | (2) |
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Unirationality of Cubic Hypersurfaces |
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237 | (2) |
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Further Examples and Applications of Degree |
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239 | (12) |
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Multidegree of a Subvariety of a Product |
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239 | (1) |
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Projective Degree of a Map |
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240 | (1) |
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Joins of Corresponding Points |
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241 | (1) |
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Varieties of Minimal Degree |
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242 | (1) |
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Degrees of Determinantal Varieties |
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243 | (1) |
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Degrees of Varieties Swept out by Linear Spaces |
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244 | (1) |
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Degrees of Some Grassmannians |
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245 | (2) |
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247 | (4) |
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Singular Points and Tangent Cones |
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251 | (15) |
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251 | (7) |
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Tangent Cones to Determinantal Varieties |
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256 | (2) |
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258 | (2) |
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Examples of Singularities |
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260 | (4) |
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Resolution of Singularities for Curves |
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264 | (2) |
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Parameter Spaces and Moduli Spaces |
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266 | (16) |
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266 | (2) |
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268 | (5) |
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273 | (2) |
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275 | (3) |
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278 | (4) |
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279 | (3) |
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282 | (26) |
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Generalities about Quadrics |
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282 | (1) |
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Tangent Spaces to Quadrics |
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283 | (1) |
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284 | (1) |
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285 | (2) |
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287 | (2) |
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Linear Spaces on Quadrics |
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289 | (6) |
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290 | (1) |
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Planes on Four-Dimensional Quadrics |
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291 | (2) |
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Fano Varieties of Quadrics in General |
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293 | (2) |
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295 | (6) |
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The Variety of Quadrics in P1 |
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295 | (1) |
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The Variety of Quadrics in P2 |
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296 | (1) |
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297 | (2) |
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299 | (2) |
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301 | (7) |
Hints for Selected Exercises |
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308 | (6) |
References |
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314 | (3) |
Index |
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317 | |