Part I Foundational material |
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3 | (10) |
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1.1 The Pythagorean Theorem |
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3 | (3) |
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6 | (2) |
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8 | (1) |
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8 | (2) |
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10 | (3) |
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13 | (46) |
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2.1 Natural numbers, mathematical induction, and the Well-ordering Principle |
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13 | (1) |
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2.2 Divisibility and prime factorization |
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14 | (8) |
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2.3 The Chinese Remainder Theorem |
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22 | (2) |
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24 | (6) |
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2.5 Polynomials modulo a prime |
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30 | (2) |
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32 | (7) |
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2.7 Digit expansions of rational numbers |
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39 | (2) |
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41 | (8) |
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49 | (4) |
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53 | (6) |
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3 Integral solutions to the Pythagorean Equation |
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59 | (22) |
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59 | (2) |
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3.2 Geometric method to find solutions |
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61 | (4) |
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3.3 Geometric method to find solutions: Non-Pythagorean examples |
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65 | (5) |
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3.4 Application: X4 + Y4 = z4 |
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70 | (2) |
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72 | (1) |
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73 | (8) |
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4 What integers are areas of right triangles? |
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81 | (10) |
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81 | (2) |
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83 | (1) |
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4.3 Connection to cubic equations |
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84 | (3) |
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87 | (1) |
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88 | (3) |
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5 What numbers are the edges of a right triangle? |
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91 | (14) |
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91 | (2) |
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93 | (2) |
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5.3 The proof of Theorem 5.2 |
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95 | (3) |
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5.4 Irreducible elements in Z[ i] |
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98 | (1) |
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99 | (2) |
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101 | (1) |
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102 | (3) |
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6 Primes of the form 4k + 1 |
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105 | (14) |
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6.1 Euclid's theorem on the infinitude of primes |
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105 | (2) |
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107 | (5) |
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6.3 An application of the Law of Quadratic Reciprocity |
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112 | (1) |
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113 | (2) |
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115 | (4) |
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7 Gauss Sums, Quadratic Reciprocity, and the Jacobi Symbol |
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119 | (14) |
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7.1 Gauss sums and Quadratic Reciprocity |
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119 | (5) |
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124 | (5) |
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129 | (1) |
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130 | (3) |
Part II Advanced Topics |
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8 Counting Pythagorean triples modulo an integer |
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133 | (18) |
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8.1 The Pythagorean Equation modulo a prime number p |
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133 | (5) |
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8.2 Solutions modulo n for a natural number n |
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138 | (7) |
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145 | (1) |
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146 | (5) |
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9 How many lattice points are there on a circle or a sphere? |
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151 | (14) |
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9.1 The case of two squares |
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151 | (4) |
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9.2 More than two squares |
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155 | (1) |
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9.3 Integral points on arcs |
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156 | (6) |
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162 | (2) |
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164 | (1) |
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165 | (22) |
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165 | (3) |
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10.2 Minkow ski's Theorem |
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168 | (4) |
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172 | (1) |
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10.4 Sums of four squares |
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173 | (3) |
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10.5 Sums of three squares |
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176 | (4) |
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180 | (2) |
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182 | (5) |
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11 Another proof of the four squares theorem |
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187 | (8) |
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187 | (2) |
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11.2 Matrix representation |
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189 | (1) |
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190 | (2) |
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192 | (1) |
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193 | (2) |
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12 Quadratic forms and sums of squares |
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195 | (16) |
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12.1 Quadratic forms with integral coefficients |
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195 | (5) |
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200 | (3) |
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203 | (3) |
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206 | (2) |
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208 | (1) |
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209 | (2) |
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13 How many Pythagorean triples are there? |
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211 | (16) |
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13.1 The asymptotic formula |
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211 | (6) |
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13.2 The computation of C2 |
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217 | (3) |
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220 | (3) |
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223 | (4) |
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14 How are rational points distributed, really? |
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227 | (20) |
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227 | (13) |
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240 | (3) |
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243 | (2) |
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245 | (2) |
Appendix A: Background |
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247 | (8) |
Appendix B: Algebraic integers |
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255 | (6) |
Appendix C: SageMath |
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261 | (10) |
References |
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271 | (6) |
Index |
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277 | |