Gruber P. Convex and Discrete Geometry

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L(P) = #(P ∩ Z d ) L o (P) = (−1) d−dim P #(relint P ∩ Z d ) L b (P) = L(P) − L o (P) for P ∈ P Z d 19 Lattice Polytopes 311 relint P is the interior of P relative to the affine hull aff P. Some authors use slightly different definitions. The systematic study of lattice point enumerators started with the work of Reeve [825,826], Macdonald [675] and the polynomiality results of Ehrhart [292–294] and is now part of the theory of valuations on P Z d . The results of Ehrhart are related to the Riemann–Roch theorem, see Brion [169]. Ehrhart polynomials and their coefficients play an essential role in combinatorics and the geometry of numbers. For references see the book of Stanley [952], the article of Henk, Schürmann and Wills [492] and the survey of Henk and Wills [493]. A relation between the roots of Ehrhart polynomials and successive minima due to Henk, Schürmann and Wills will be stated in Sect. 23.1. This section contains the proofs of two results of Ehrhart, following in part the line of Macdonald [675]. Different proofs will be given in Sect. 19.4, using the theorem of Betke and Kneser. For more information the reader is referred to Ehrhart’s monograph [294], to the books cited in the introduction of Sect. 19 and to the surveys of McMullen and Schneider [716], Gritzmann and Wills [397], Brion [170] and Simion [940]. Beck, De Loera, Develin, Pfeifle and Stanley [85] investigated the coefficients and roots of the Ehrhart polynomials. Ehrhart’s Polynomiality and Reciprocity Results for L and L o The following results are due to Ehrhart [292–294]. The first result is called Ehrhart’s polynomiality theorem, the second Ehrhart’s reciprocity theorem. Theorem 19.1. Let P be a proper convex lattice polytope in E d . Then the following claims hold: (i) L(nP) = pP(n) for n ∈ N, where pP is a polynomial of degree d, with leading coefficient V (P) and constant term 1. (ii) L o (nP) = (−1) d pP(−n) for n ∈ N. These results yield the Reeve–Macdonald formulae for the volume of lattice polytopes, see Sect. 19.2. In our proof of the theorem, the notion of lattice and simple related concepts are used, for which the reader may wish to consult Sect. 21. Proof. (i) First, the following will be shown. (1) Let S ∈ PZd p be a simplex. Then ∞� L(nS)t n � � d + 1 � � d + 2 � = q(t) 1 + t + t 1 2 2 � +··· for |t| < 1, n=0 where q is a polynomial of degree at most d with integer coefficients.
312 Convex Polytopes Embed E d into E d+1 as usual (first d coordinates) and let q1,...,qd+1 ∈ Z d+1 be the vertices of the lattice simplex T = S + (0,...,0, 1) in the hyperplane {x : xd+1 = 1}. The lattice Z d+1 has determinant d(Z d+1 ) = 1. Let L be the sublattice of Z d+1 with basis {q1,...,qd+1}.ThesetF ={α1q1 +···+αd+1qd+1 : 0 ≤ αi < 1} is a fundamental parallelotope of L. Thus, for the determinant of L we have d(L) = Vd+1(F), where Vd+1 stands for the volume in E d+1 . Then the following hold. (2) For each u ∈ Z d+1 , there is precisely one point v ∈ F ∩ Z d+1 such that u ∈ v + L. Further, Vd+1(F) = #(F ∩ Z d+1 ) = h, say. If u = β1q1 +···+βd+1qd+1 ∈ Z d+1 , then v = (β1 −⌊β1⌋)q1 +···+(βd+1 − ⌊βd+1⌋)qd+1 is the unique point v ∈ F ∩ Z d+1 with u ∈ v + L. The index of the sublattice (subgroup) L in the lattice (group) Z d+1 is thus #(F ∩ Z d+1 ). Since the index is also equal to d(L)/d(Z d+1 ) = Vd+1(F), we see that Vd+1(F) = #(F ∩ Z d+1 ), concluding the proof of (2). Compare Sect. 21.3. For each u ∈ nT ∩ Z d+1 , according to (2), we have �d+1 (3) u = v + miqi with suitable integers mi ≥ 0. i=1 To see this, note that u = β1q1 +···+βd+1qd+1 with βi ≥ 0 and put mi =⌊βi⌋. Considering the last coordinate, (3) shows that �d+1 (4) n = vd+1 + mi with integers mi ≥ 0. i=1 Conversely, given v ∈ F ∩ Z d+1 , any solution of (4) in integers mi ≥ 0 gives rise to a unique point u ∈ nT ∩ Z d+1 with u ∈ v + L. The number of such solutions of (4) equals the coefficient of t n in the power series t vd+1 2 d+1 t (1 + t + t +···) = vd+1 (1 − t) d+1 = t vd+1 � � � � � −d − 1 −d − 1 1 + (−t) + (−t) 1 2 2 � +··· = t vd+1 � � � � � d + 1 d + 2 1 + t + t 1 2 2 � +··· , where we have applied Newton’s binomial series. Hence (5) L(nS)(= L(nT)) equals the coefficient of tn in the power series � � � � � d + 1 d + 2 q(t) 1 + t + t 1 2 2 � +··· , where q(t) = � v∈F∩Z d+1 t vd+1 . To determine the degree of q(·), note that each v ∈ F ∩ Z d+1 can be represented in the form v = α1q1 +···αd+1qd+1 where 0 ≤ αi < 1. Each qi has last coordinate
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Grundlehren der mathematischen Wiss
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Peter M. Gruber Institute of Discre
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VI Preface theory of finite groups
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Contents Preface ..................
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Contents XI 12 Special Convex Bodie
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Contents XIII 29 Packing of Balls a
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2 Convex Functions 1 Convex Functio
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4 Convex Functions x epi f f C y Fi
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6 Convex Functions Together these i
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8 Convex Functions Theorem 1.4. Let
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10 Convex Functions z = f (x) + f
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12 Convex Functions 1.3 Convexity C
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14 Convex Functions Proof (by affin
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16 Convex Functions Minkowski’s I
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18 Convex Functions (ii) Let x > 0.
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20 Convex Functions 2 Convex Functi
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22 Convex Functions | f (z) − f (
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24 Convex Functions First-Order Dif
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26 Convex Functions Remark. More pr
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28 Convex Functions even more is tr
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30 Convex Functions G(x). The proof
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32 Convex Functions by (15), unifor
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34 Convex Functions 2.4 A Stone-Wei
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36 Convex Functions x x Fig. 2.1. S
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38 Convex Functions F is convex. Us
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40 Convex Bodies results, character
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42 Convex Bodies Convex Hulls Given
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44 Convex Bodies The next result is
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46 Convex Bodies C ∩ L ⊥ clearl
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48 Convex Bodies Suppose not. Then,
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50 Convex Bodies The Centrepoint of
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52 Convex Bodies Since G is open, w
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54 Convex Bodies in one of the two
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56 Convex Bodies or geometric infor
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58 Convex Bodies v HC (u, h(u)) (v,
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60 Convex Bodies C D Fig. 4.3. Sepa
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62 Convex Bodies For the proof of t
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64 Convex Bodies in contradiction t
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66 Convex Bodies (6) R(t) ⊆ E d i
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68 Convex Bodies 5 The Boundary of
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70 Convex Bodies for all y ∈ C an
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72 Convex Bodies the existence of s
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74 Convex Bodies where r(·) is a s
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76 Convex Bodies Hence x ∈ conv e
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78 Convex Bodies N = � � X, O Y
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80 Convex Bodies Further topics of
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82 Convex Bodies We are now ready t
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84 Convex Bodies similarly, D j is
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86 Convex Bodies For the proof of t
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88 Convex Bodies The definition of
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90 Convex Bodies If ei ∈ Pi is no
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92 Convex Bodies Let v(·) denote (
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94 Convex Bodies The present sectio
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96 Convex Bodies Proposition 6.5. L
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98 Convex Bodies Thus Second, Minko
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100 Convex Bodies The Valuation Pro
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102 Convex Bodies Minkowski’s the
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104 Convex Bodies To remedy the sit
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106 Convex Bodies Proof. Applying S
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108 Convex Bodies Third, let C be a
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110 Convex Bodies A Problem of Sant
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112 Convex Bodies sets of S. Ifφ c
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114 Convex Bodies = � (−1) |J|
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116 Convex Bodies If P has dimensio
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118 Convex Bodies Since, by Volland
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120 Convex Bodies that is, V is sim
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122 Convex Bodies Let C, D ∈ C su
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124 Convex Bodies P Q . . . . Fig.
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126 Convex Bodies 7.3 Characterizat
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128 Convex Bodies and the Bi have p
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130 Convex Bodies Since the Riemann
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132 Convex Bodies Seventh, o v3 v2
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134 Convex Bodies Mean Width and th
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136 Convex Bodies � χ(C ∩ mD)
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138 Convex Bodies In the following,
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140 Convex Bodies 7.5 Hadwiger’s
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142 Convex Bodies 8.1 The Classical
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144 Convex Bodies C ∩ H(tC ) C D
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146 Convex Bodies Theorem 8.4. Let
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148 Convex Bodies In the following
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150 Convex Bodies Integration impli
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152 Convex Bodies As a consequence
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154 Convex Bodies Proof. � 1 2 w(
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156 Convex Bodies Let ϱ>0 be the m
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158 Convex Bodies Wulff’s Theorem
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160 Convex Bodies Third, by (8) and
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162 Convex Bodies Since the measure
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164 Convex Bodies An application of
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166 Convex Bodies Since f has Lipsc
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168 Convex Bodies Clearly, the inte
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170 Convex Bodies Note that �st :
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172 Convex Bodies Proposition 9.2.
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174 Convex Bodies Proof. Let ε>0.
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176 Convex Bodies The Brunn-Minkows
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178 Convex Bodies 9.3 Schwarz Symme
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180 Convex Bodies Torsional Rigidit
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182 Convex Bodies The proof of (3)
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184 Convex Bodies � �� 2 2
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188 Convex Bodies Both problems inf
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190 Convex Bodies The Area Measure
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192 Convex Bodies halfspace {z : un
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194 Convex Bodies Let σm be the di
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196 Convex Bodies Thus Minkowski’
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198 Convex Bodies Suppose now that
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200 Convex Bodies vector of St at x
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202 Convex Bodies Outer Billiards F
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204 Convex Bodies For more informat
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206 Convex Bodies with P. Thus, it
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208 Convex Bodies Note that ui ∈
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212 Convex Bodies the maximum of th
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214 Convex Bodies (20) mni ≥ 1 λ
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216 Convex Bodies Prove analogous r
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218 Convex Bodies Heuristic Princip
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220 Convex Bodies λC + x νC + z
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222 Convex Bodies To show that (K +
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224 Convex Bodies The integral here
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226 Convex Bodies In the following
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228 Convex Bodies The first such re
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230 Convex Bodies v o Fig. 12.3. Sy
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232 Convex Bodies What Does the Bou
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234 Convex Bodies Corollary 13.1. L
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236 Convex Bodies Hence ν = 0 and
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238 Convex Bodies geometry, see Sei
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240 Convex Bodies We distinguish th
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242 Convex Bodies by Proposition 13
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244 Convex Polytopes The material i
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246 Convex Polytopes V-Polytopes an
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248 Convex Polytopes Convex cones w
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250 Convex Polytopes Generalized Co
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252 Convex Polytopes d 2 inequaliti
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254 Convex Polytopes The Face Latti
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256 Convex Polytopes Then (6) impli
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258 Convex Polytopes P in F. For an
Page 271 and 272: 260 Convex Polytopes Euler’s Poly
Page 273 and 274: 262 Convex Polytopes bijection betw
Page 275 and 276: 264 Convex Polytopes The Converse o
Page 277 and 278: 266 Convex Polytopes (geometric) fa
Page 279 and 280: 268 Convex Polytopes consists preci
Page 281 and 282: 270 Convex Polytopes The Lower and
Page 283 and 284: 272 Convex Polytopes A problem of S
Page 285 and 286: 274 Convex Polytopes The first cond
Page 287 and 288: 276 Convex Polytopes The existence
Page 289 and 290: 278 Convex Polytopes For d = 3 it f
Page 291 and 292: 280 Convex Polytopes 16 Volume of P
Page 293 and 294: 282 Convex Polytopes by (2). Hence
Page 295 and 296: 284 Convex Polytopes (12) The volum
Page 297 and 298: 286 Convex Polytopes T ∩ Z, respe
Page 299 and 300: 288 Convex Polytopes An Alternative
Page 301 and 302: 290 Convex Polytopes P clearly can
Page 303 and 304: 292 Convex Polytopes 17 Rigidity Ri
Page 305 and 306: 294 Convex Polytopes Fig. 17.2. Cau
Page 307 and 308: 296 Convex Polytopes Call the index
Page 309 and 310: 298 Convex Polytopes of V. Fori ∈
Page 311 and 312: 300 Convex Polytopes Thus (3) impli
Page 313 and 314: 302 Convex Polytopes Proof. (i)⇒(
Page 315 and 316: 304 Convex Polytopes For other pert
Page 317 and 318: 306 Convex Polytopes where λ is a
Page 319 and 320: 308 Convex Polytopes 18.3 The Isope
Page 321: 310 Convex Polytopes 19 Lattice Pol
Page 325 and 326: 314 Convex Polytopes To see this, n
Page 327 and 328: 316 Convex Polytopes The Coefficien
Page 329 and 330: 318 Convex Polytopes If the triangl
Page 331 and 332: 320 Convex Polytopes � qP(t) = No
Page 333 and 334: 322 Convex Polytopes Now, take into
Page 335 and 336: 324 Convex Polytopes L � P + (n +
Page 337 and 338: 326 Convex Polytopes V (S) = V .Let
Page 339 and 340: 328 Convex Polytopes (7) ψ|H d = 0
Page 341 and 342: 330 Convex Polytopes Theorem 19.6.
Page 343 and 344: 332 Convex Polytopes (15) L(nP) = L
Page 345 and 346: 334 Convex Polytopes have to be sin
Page 347 and 348: 336 Convex Polytopes economics, von
Page 349 and 350: 338 Convex Polytopes Existence of S
Page 351 and 352: 340 Convex Polytopes Description of
Page 353 and 354: 342 Convex Polytopes (6) u piai xq
Page 355 and 356: 344 Convex Polytopes For x ∈ Bd
Page 357 and 358: 346 Convex Polytopes Rational Polyh
Page 359 and 360: 348 Convex Polytopes Totally Dual I
Page 361 and 362: 350 Convex Polytopes of the vectors
Page 363 and 364: Geometry of Numbers and Aspects of
Page 365 and 366: Extension to Crystallographic Group
Page 367 and 368: Relations Between Different Bases 2
Page 369 and 370: 21 Lattices 359 triangle conv{o,(u,
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21 Lattices 363 A similar, slightly
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21.4 Polar Lattices 21 Lattices 365
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The First Fundamental Theorem 22 Mi
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22 Minkowski’s First Fundamental
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If 22 Minkowski’s First Fundament
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22 Minkowski’s First Fundamental
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Proof. Consider the linear forms l1
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Proof. It is sufficient to consider
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Thus V (C) ≥ V (O) = 2d � �
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Given C and L, the problem arises t
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23 Successive Minima 383 as require
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24 The Minkowski-Hlawka Theorem 24
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(6) (V (J) ≈) � n�= 0 (7) J
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24 The Minkowski-Hlawka Theorem 389
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The Variance Theorem of Rogers and
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The Selection Theorem of Mahler [68
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26 The Torus Group E d /L 395 where
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Proposition 26.2. E d /L is a compa
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26 The Torus Group E d /L 399 theor
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26 The Torus Group E d /L 401 The m
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The formula to calculate the Jordan
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27 Special Problems in the Geometry
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Asymptotic Estimates 27 Special Pro
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27 Special Problems in the Geometry
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28 Basis Reduction and Polynomial A
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(ii) �b1� ≤2 1 2 (d−1) min
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28 Basis Reduction and Polynomial A
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and so 28 Basis Reduction and Polyn
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Shortest Lattice Vector Problem 28
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and therefore �x − m� 2 = �
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29 Packing of Balls and Positive Qu
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29.3 Error Correcting Codes and Bal
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30 Packing of Convex Bodies 439 The
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30 Packing of Convex Bodies 441 Nex
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Packing and Central Symmetrization
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Existence of Densest Lattice Packin
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30 Packing of Convex Bodies 447 Rem
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A Lower Estimate for the Maximum La
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Lattice Packing and Packing of Tran
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a f b o e 2D c Fig. 30.3. Disc and
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31 Covering with Convex Bodies 455
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32 Tiling with Convex Polytopes 463
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Define 32 Tiling with Convex Polyto
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33.1 Fejes Tóth’s Inequality for
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Noting that 2h 2 v − hhvv = 2π 2
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33 Optimum Quantization 485 The con
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(7) � (x, y) : x ∈ K, 0 ≤ y
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Next, we prove that (18) lim inf n
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Generalizations 33 Optimum Quantiza
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33 Optimum Quantization 493 set wit
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33 Optimum Quantization 495 In (4)
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33 Optimum Quantization 497 encoder
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34 Koebe’s Representation Theorem
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G 34 Koebe’s Representation Theor
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Di+1 34 Koebe’s Representation Th
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References 1. Achatz, H., Kleinschm
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References 515 36. Arias de Reyna,
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References 517 88. Beer, G., Topolo
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References 519 136. Bohr, H., Molle
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References 521 190. Carathéodory,
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References 523 237. Dantzig, G.B.,
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References 525 286. Edmonds, A.L.,
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References 527 337. Florian, A., Ex
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References 529 385. Goodman, J.E.,
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References 531 435. Gruber, P.M., C
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References 533 487. Heil, E., Über
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References 535 534. Hyuga, T., An e
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References 537 582. Khovanskiĭ (Ho
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References 539 632. Lazutkin, V.F.,
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References 541 684. Mani-Levitska,
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References 543 736. Minkowski, H.,
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References 545 783. Pach, J., Agarw
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References 547 835. Rickert, N.W.,
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References 549 891. Schmidt, E., Di
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References 551 941. Skubenko, B.F.,
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References 553 992. Teissier, B., V
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References 555 1042. Zassenhaus, H.
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558 INDEX Bravais classification of
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560 INDEX existence of elementary v
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562 INDEX Kneser-Macbeath theorem,
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564 INDEX rational lattice, 414 rat
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566 INDEX transference theorem of K
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568 AUTHOR INDEX Björner, 265 Blas
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570 AUTHOR INDEX Giles, J., 1 Giles
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572 AUTHOR INDEX Kuczma, 13, 17 Kü
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574 AUTHOR INDEX Pick, 316 Pisier,
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576 AUTHOR INDEX Tanemura, 464 Tarj
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578 List of Symbols sch, schL Schwa
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289. Manin: Gauge Field Theory and
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