Preface |
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vii | |
Overview |
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xi | |
Notation |
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xxiii | |
Contents |
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xxvii | |
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1 | (64) |
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1 | (4) |
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1.1 Warm up. Lifting of continuous maps: local and global aspects |
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5 | (6) |
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1.2 Lifting of §1-valued maps in W1,p Definition of Ju |
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11 | (11) |
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22 | (1) |
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1.4 Lifting of §1-valued maps in W1,1 and BV. Definition of Σ(u) |
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23 | (14) |
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1.5 Σ(u) computed via duality: the basic relation between Σ{u) and Ju |
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37 | (7) |
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1.6 An excursion into Monge--Kantorovich (=MK) territory |
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44 | (5) |
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49 | (2) |
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1.8 Least energy with prescribed Jacobian |
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51 | (1) |
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1.9 Complements and open problems |
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52 | (4) |
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56 | (9) |
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2 The geometry of Ju and Σ(u) in 2D; point singularities and minimal connections |
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65 | (68) |
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65 | (6) |
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2.1 Ju as a sum of Dirac masses |
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71 | (5) |
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2.2 Where optimal transport (=OT) enters: the quantity L(a, d) and minimal configurations |
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76 | (12) |
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2.3 Returning to u: Σ(h) = 2πL(a, d) |
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88 | (3) |
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2.4 Σ(u) = S1(u) ≥ 2π L(a, d) via the coarea formula |
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91 | (3) |
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2.5 Σ(u) = S1(u) ≤ 2π L(a, d) via the dipole construction |
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94 | (2) |
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2.6 Σ(u) ≤ ∫Ω|Vu| + 2πL(a, d) via minimal configurations |
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96 | (5) |
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2.7 Connections associated with (a, d). Minimal connections |
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101 | (4) |
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2.8 Returning to u: a bijective correspondence between BV liftings and connections |
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105 | (2) |
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2.9 Describing Ju and Σ(u) for a general u W1,1 |
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107 | (12) |
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2.10 An integral representation of the distribution Ju |
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119 | (4) |
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2.11 Complements and open problems |
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123 | (5) |
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128 | (5) |
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3 The geometry of Ju and Σ(u) in 3D (and higher); line singularities and minimal surfaces |
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133 | (40) |
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133 | (2) |
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3.1 Examples. Ju as path integration |
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135 | (7) |
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3.2 Σ(u) as a least area: E(u) = 2πA0(Γ) |
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142 | (3) |
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3.3 Σ(u) ≥ 2πA0(Γ) via the coarea formula |
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145 | (3) |
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3.4 Σ(u) ≤ 2πA0(Γ) via the dipole construction |
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148 | (1) |
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3.5 Least area spanned by a contour from the perspective of MK |
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149 | (1) |
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3.6 The structure of Ju for a general u W1,1. Where Federer encounters Kantorovich |
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150 | (7) |
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3.7 Further properties when Ju is a measure |
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157 | (3) |
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3.8 Complements and open problems |
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160 | (10) |
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170 | (3) |
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4 A digression: sphere-valued maps |
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173 | (32) |
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173 | (4) |
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4.1 The "historical" case: N = 3 and k = 2, where everything fits into place! |
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177 | (6) |
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4.2 A distinguished class of currents. Definition of F1 |
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183 | (3) |
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4.3 The case N = 4 and k = 2; where complications appear |
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186 | (4) |
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4.4 The general case: N ≥ 2 and 1 ≤ k ≤ N - 1 |
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190 | (6) |
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4.5 Complements and open problems |
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196 | (5) |
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201 | (4) |
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5 Lifting in fractional Sobolev spaces and in VMO |
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205 | (22) |
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205 | (1) |
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5.1 Lifting of §1-valued maps in fractional Sobolev spaces |
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206 | (10) |
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5.2 Lifting of §1-valued maps in VMO and BMO |
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216 | (7) |
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5.3 Lifting in Ws,p, sp < 1, upgraded |
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223 | (1) |
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5.4 Complements and open problems |
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224 | (1) |
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225 | (2) |
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6 Uniqueness of lifting and beyond |
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227 | (26) |
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227 | (1) |
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6.1 Constancy in VMO (Ω; Z) |
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228 | (1) |
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6.2 Constancy in W1,1 (Ω; Z) |
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229 | (1) |
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6.3 Constancy in W1/p-p(Ω; Z), 1 < p < ∞ |
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229 | (5) |
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6.4 Connectedness of the essential range |
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234 | (1) |
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6.5 A new function space. Applications to sums |
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235 | (5) |
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6.6 Proof of Theorem 6.2 (the BBM formula) |
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240 | (2) |
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6.7 Complements and open problems |
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242 | (8) |
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250 | (3) |
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253 | (26) |
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253 | (2) |
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255 | (3) |
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7.2 Outline of the proof of Theorem 7.1 |
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258 | (1) |
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7.3 A glimpse of the theory of weighted Sobolev spaces |
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259 | (1) |
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260 | (14) |
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7.5 Complements and open problems |
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274 | (3) |
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277 | (2) |
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8 Applications of the factorization |
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279 | (20) |
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279 | (1) |
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8.1 Existence of Ju for u in W1/p,p |
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280 | (5) |
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285 | (3) |
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8.3 Least energy with prescribed Jacobian |
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288 | (1) |
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289 | (2) |
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291 | (1) |
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8.6 Minimizing the BV part of the phase |
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292 | (2) |
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8.7 Complements and open problems |
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294 | (3) |
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297 | (2) |
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9 Estimates of phases: positive and negative results |
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299 | (12) |
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299 | (1) |
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300 | (1) |
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300 | (2) |
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9.3 N = 1, s = 1/p, and p < 1 |
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302 | (1) |
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9.4 N = 1, 0 < 5 < 1, and sp < 1 |
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303 | (1) |
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9.5 N ≥ 2, 0 < 5 < 1, and sp ≤ N |
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304 | (1) |
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9.6 N ≥ 2, 0 < 5 < 1, and 1 ≤ sp < N |
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304 | (2) |
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9.7 Complements and open problems |
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306 | (2) |
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308 | (3) |
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311 | (20) |
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311 | (1) |
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10.1 When are smooth maps dense? |
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312 | (1) |
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10.2 Density of 3%. Answer to Question 1 |
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313 | (5) |
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10.3 Characterization of C00(Q; S1) Answer to Question 2 |
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318 | (2) |
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10.4 Weak sequential density. Answer to Question 3 |
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320 | (1) |
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10.5 Distance to smooth maps |
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320 | (4) |
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10.6 Complements and open problems |
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324 | (3) |
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327 | (4) |
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331 | (8) |
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331 | (1) |
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11.1 Proof of Theorem 11.1 |
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332 | (2) |
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11.2 A sharp form of the extension problem |
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334 | (1) |
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11.3 Complements and open problems |
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334 | (2) |
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336 | (3) |
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339 | (42) |
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339 | (1) |
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340 | (4) |
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12.2 Degree, lifting, and traces in Ws,p(§; §1) |
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344 | (1) |
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12.3 Integral representations for the degree |
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345 | (5) |
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12.4 A "distributional degree" |
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350 | (2) |
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12.5 Estimates for the degree |
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352 | (6) |
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358 | (1) |
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12.7 Degree and Fourier coefficients |
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358 | (6) |
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12.8 Complements and open problems |
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364 | (15) |
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379 | (2) |
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13 Dirichlet problems. Gaps. Infinite energies |
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381 | (22) |
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381 | (1) |
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13.1 Minimizing the W1,p energy when p ≥ 2 |
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382 | (1) |
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13.2 Minimizing the W1,p energy when 1 < p < 2 |
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383 | (3) |
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386 | (2) |
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13.4 More about minimizers when Ω = D and 1 < p < 2 |
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388 | (2) |
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13.5 Further regularity and no gap for p < 2, near p = 2, when N = 2 |
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390 | (4) |
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13.6 Complements and open problems |
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394 | (7) |
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401 | (2) |
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403 | (28) |
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403 | (1) |
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14.1 Lifting in W1,p(Ω; §1) revisited |
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403 | (6) |
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14.2 Relaxed energy revisited |
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409 | (8) |
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14.3 Lifting in Ws,p(Ω; §1) revisited |
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417 | (4) |
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14.4 Density in Ws,p(Ω; §1) revisited |
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421 | (2) |
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423 | (2) |
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14.6 Complements and open problems |
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425 | (5) |
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430 | (1) |
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431 | (92) |
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431 | (4) |
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15.2 Sobolev embeddings and Gagliardo--Nirenberg inequalities |
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435 | (6) |
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15.3 Composition in Sobolev spaces |
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441 | (2) |
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15.4 Standard (and non-standard) examples of maps in Sobolev spaces |
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443 | (8) |
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15.5 Further results on BMO and VMO |
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451 | (10) |
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461 | (6) |
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15.7 Fine theory of BV maps |
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467 | (8) |
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15.8 Description of (minimal) connections associated with (a, d) |
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475 | (14) |
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489 | (4) |
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15.10 Jacobians of W1,p(Ω; §) maps |
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493 | (3) |
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15.11 When Ju is a measure |
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496 | (1) |
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15.12 Products in fractional Sobolev spaces |
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497 | (2) |
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499 | (1) |
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500 | (23) |
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507 | (16) |
Symbol Index |
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523 | (2) |
Subject Index |
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525 | (2) |
Author Index |
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527 | |