Table of Contents
1 Elementary Bifurcations 1
1.1 Bifurcations in Dimension 1 1
1.1.1 Saddle-Node Bifurcation 2
1.1.2 Pitchfork Bifurcation 5
1.2 Bifurcations in Dimension 2 8
1.2.1 Hopf Bifurcation 9
1.2.2 Example: Homogeneous Brusselator 18
1.2.3 Hopf Bifurcation with SO(2) Symmetry 22
1.2.4 Steady Bifurcation with O(2) Symmetry 24
2 Center Manifolds 29
2.1 Notations 29
2.2 Local Center Manifolds 30
2.2.1 Hypotheses 30
2.2.2 Main Result 34
2.2.3 Checking Hypothesis 2.7 36
2.2.4 Examples 38
2.3 Particular Cases and Extensions 46
2.3.1 Parameter-Dependent Center Manifolds 46
2.3.2 Nonautonomous Center Manifolds 51
2.3.3 Symmetries and Reversibility 53
2.3.4 Empty Unstable Spectrum 58
2.4 Further Examples and Exercises 59
2.4.1 A Fourth Order ODE 60
2.4.2 Burgers Model 63
2.4.3 Swift-Hohenberg Equation 70
2.4.4 Brusselator Model 81
2.4.5 Elliptic PDE in a Strip 89
3 Normal Forms 93
3.1 Main Theorem 93
3.1.1 Proof of Theorem 1.2 95
3.1.2 Examples in Dimension 2: iω, 02 99
3.1.3 Examples in Dimension 3: 0(iω), 03 104
3.1.4 Examples in Dimension 4: (iω1) (iω2), (iω)2, 02(iω), 0202 106
3.2 Parameter-Dependent Normal Forms 109
3.2.1 Main Result 109
3.2.2 Linear Normal Forms 111
3.2.3 Derivation of the Parameter-Dependent Normal Form 112
3.2.4 Example: 02 Normal Form with Parameters 114
3.3 Symmetries and Reversibility 116
3.3.1 Equivariant Vector Fields 117
3.3.2 Reversible Vector Fields 118
3.3.3 Example: van der Pol System 120
3.4 Normal Forms for Reduced Systems on Center Manifolds 122
3.4.1 Computation of Center Manifolds and Normal Forms 122
3.4.2 Example 1: Hopf Bifurcation 124
3.4.3 Example 2: Hopf Bifurcations with Symmetries 127
3.4.4 Example 3: Takens-Bogdanov Bifurcation 134
3.4.5 Example 4: (iω1)(iω2) bifurcation 139
3.5 Further Normal Forms 144
3.5.1 Time-Periodic Normal Forms 144
3.5.2 Example: Periodically Forced Hopf Bifurcation 147
3.5.3 Normal Forms for Analytic Vector Fields 152
4 Reversible Bifurcations 157
4.1 Dimension 2 157
4.1.1 Reversible Takens-Bogdanov Bifurcation 02+ 160
4.1.2 Reversible Takens-Bogdanov Bifurcation 02- 172
4.2 Dimension 3 179
4.2.1 Reversible 03+ Bifurcation 180
4.2.2 Reversible 03- Bifurcation (Elements) 191
4.2.3 Reversible 002 Bifurcation (Elements) 193
4.2.4 Reversible 0(iω) Bifurcation (Elements) 195
4.3 Dimension 4 197
4.3.1 Reversible 02+(iω) Bifurcation 198
4.3.2 Reversible 02-(iω) Bifurcation (Elements) 210
4.3.3 Reversible (iω)2 Bifurcation (1-1 resonance) 214
4.3.4 Reversible (iω1)(iω2) Bifurcation (Elements) 226
4.3.5 Reversible 04+ Bifurcation (Elements) 229
4.3.6 Reversible 0202 Bifurcation with SO(2) Symmetry 234
5 Applications 239
5.1 Hydrodynamic Instabilities 239
5.1.1 Hydrodynamic Problem 239
5.1.2 Couette-Taylor Problem 244
5.1.3 Bénard-Rayleigh Convection Problem 249
5.2 Existence of Traveling Waves 258
5.2.1 Gravity-Capillary Water-Waves 259
5.2.2 Almost-Planar Waves in Reaction-Diffusion Systems 270
5.2.3 Waves in Lattices 275
Appendix 279
A Elements of Functional Analysis 279
A.1 Bounded and Closed Operators 279
A.2 Resolvent and Spectrum 280
A.3 Compact Operators and Operators with Compact Resolvent 282
A.4 Adjoint Operator 283
A.5 Fredholm Operators 284
A.6 Basic Sobolev Spaces 284
B Center Manifolds 287
B.1 Proof of Theorem 2.9 (Center Manifolds) 287
B.2 Proof of Theorem 2.17 (Semilinear Case) 293
B.3 Proof of Theorem 3.9 (Nonautonomous Vector Fields) 298
B.4 Proof of Theorem 3.13 (Equivariant Systems) 299
B.5 Proof of Theorem 3.22 (Empty Unstable Spectrum) 300
C Normal Forms 301
C.1 Proof of Lemma 1.13 (03 Normal Form) 302
C.2 Proof of Lemma 1.17 ((iω)2 Normal Form) 303
C.3 Proof of Lemma 1.18 (02(iω) Normal Form) 305
C.4 Proof of Lemma 1.19 (0202 Normal Form) 307
C.5 Proof of Theorem 2.2 (Perturbed Normal Forms) 308
D Reversible Bifurcations 310
D.1 03+ Normal Form in Infinite Dimensions 310
D.2 (iω)2 Normal Form in Infinite Dimensions 315
References 321
Index 327