Synchronization phenomena and collective behavior are commonplace in complex systems with applications ranging from biological processes such as coordinated neuron firings and cell cycles to the stability of alternating current power grids. A fundamental pursuit is the study of how various types of symmetry—e.g., as manifest in network structure or coupling dynamics—impact a system’s collective behavior. Understanding the intricate relations between structural and dynamical symmetry/asymmetry also provides new paths to develop strategies that enhance or inhibit synchronization. Previous research has revealed symmetry as a key factor in identifying optimization mechanisms, but the particular ways that symmetry/asymmetry influence collective behavior can generally depend on the type of dynamics, networks, and form of synchronization (e.g., phase synchronization, group synchronization, and chimera states). Other factors, such as time delay, noise, time-varying structure, multilayer connections, basin stability, and transient dynamics, also play important roles, and many of these remain underexplored. This Focus Issue brings together a survey of theoretical and applied research articles that push forward this important line of questioning.

1.
G.
Ermentrout
and
N.
Kopell
, “
Oscillator death in systems of coupled neural oscillators
,”
SIAM J. Appl. Math.
50
,
125
146
(
1990
).
2.
S. F.
Muldoon
,
I.
Soltesz
, and
R.
Cossart
, “
Spatially clustered neuronal assemblies comprise the microstructure of synchrony in chronically epileptic networks
,”
Proc. Natl. Acad. Sci. U.S.A.
110
,
3567
3572
(
2013
).
3.
A.
Karma
, “
Electrical alternans and spiral wave breakup in cardiac tissue
,”
Chaos
4
,
461
472
(
1994
).
4.
A. T.
Winfree
,
The Geometry of Biological Time
(
Springer Science & Business Media
,
2001
), Vol. 12.
5.
F.
Dorfler
and
F.
Bullo
, “
Synchronization and transient stability in power networks and nonuniform kuramoto oscillators
,”
SIAM J. Control Optim.
50
,
1616
1642
(
2012
).
6.
A. E.
Motter
,
S. A.
Myers
,
M.
Anghel
, and
T.
Nishikawa
, “
Spontaneous synchrony in power-grid networks
,”
Nat. Phys.
9
,
191
197
(
2013
).
7.
P. S.
Skardal
and
A.
Arenas
, “
Control of coupled oscillator networks with application to microgrid technologies
,”
Sci. Adv.
1
,
e1500339
(
2015
).
8.
Y.
Kuramoto
,
Chemical Oscillations, Waves, and Turbulence
(
Springer Science & Business Media
,
2012
).
9.
L. M.
Pecora
and
T. L.
Carroll
, “
Master stability functions for synchronized coupled systems
,”
Phys. Rev. Lett.
80
,
2109
(
1998
).
10.
M. G.
Rosenblum
,
A. S.
Pikovsky
, and
J.
Kurths
, “
Phase synchronization of chaotic oscillators
,”
Phys. Rev. Lett.
76
,
1804
(
1996
).
11.
J. F.
Totz
,
J.
Rode
,
M. R.
Tinsley
,
K.
Showalter
, and
H.
Engel
, “
Spiral wave chimera states in large populations of coupled chemical oscillators
,”
Nat. Phys.
14
,
282
285
(
2018
).
12.
P. S.
Skardal
,
E.
Ott
, and
J. G.
Restrepo
, “
Cluster synchrony in systems of coupled phase oscillators with higher-order coupling
,”
Phys. Rev. E
84
,
036208
(
2011
).
13.
L. M.
Pecora
,
F.
Sorrentino
,
A. M.
Hagerstrom
,
T. E.
Murphy
, and
R.
Roy
, “
Cluster synchronization and isolated desynchronization in complex networks with symmetries
,”
Nat. Commun.
5
,
4079
(
2014
).
14.
G.
Osipov
and
M.
Sushchik
, “
Synchronized clusters and multistability in arrays of oscillators with different natural frequencies
,”
Phys. Rev. E
58
,
7198
(
1998
).
15.
D.
Taylor
,
E.
Ott
, and
J. G.
Restrepo
, “
Spontaneous synchronization of coupled oscillator systems with frequency adaptation
,”
Phys. Rev. E
81
,
046214
(
2010
).
16.
E.
Ott
and
T. M.
Antonsen
, “
Low dimensional behavior of large systems of globally coupled oscillators
,”
Chaos
18
,
037113
(
2008
).
17.
E.
Ott
and
T. M.
Antonsen
, “
Long time evolution of phase oscillator systems
,”
Chaos
19
,
023117
(
2009
).
18.
S. H.
Strogatz
, “
From kuramoto to crawford: Exploring the onset of synchronization in populations of coupled oscillators
,”
Physica D
143
,
1
20
(
2000
).
19.
S.
Boccaletti
,
J.
Kurths
,
G.
Osipov
,
D.
Valladares
, and
C.
Zhou
, “
The synchronization of chaotic systems
,”
Phys. Rep.
366
,
1
101
(
2002
).
20.
J. A.
Acebrón
,
L. L.
Bonilla
,
C. J. P.
Vicente
,
F.
Ritort
, and
R.
Spigler
, “
The Kuramoto model: A simple paradigm for synchronization phenomena
,”
Rev. Mod. Phys.
77
,
137
(
2005
).
21.
F. A.
Rodrigues
,
T. K. D.
Peron
,
P.
Ji
, and
J.
Kurths
, “
The Kuramoto model in complex networks
,”
Phys. Rep.
610
,
1
98
(
2016
).
22.
A.
Arenas
,
A.
Díaz-Guilera
,
J.
Kurths
,
Y.
Moreno
, and
C.
Zhou
, “
Synchronization in complex networks
,”
Phys. Rep.
469
,
93
153
(
2008
).
23.
M.
Barahona
and
L. M.
Pecora
, “
Synchronization in small-world systems
,”
Phys. Rev. Lett.
89
,
054101
(
2002
).
24.
J.
Gómez-Gardeñes
,
Y.
Moreno
, and
A.
Arenas
, “
Synchronizability determined by coupling strengths and topology on complex networks
,”
Phys. Rev. E
75
,
066106
(
2007
).
25.
J. G.
Restrepo
,
E.
Ott
, and
B. R.
Hunt
, “
Onset of synchronization in large networks of coupled oscillators
,”
Phys. Rev. E
71
,
036151
(
2005
).
26.
J. G.
Restrepo
,
E.
Ott
, and
B. R.
Hunt
, “
Emergence of synchronization in complex networks of interacting dynamical systems
,”
Physica D
224
,
114
122
(
2006
).
27.
B.
Coutinho
,
A.
Goltsev
,
S.
Dorogovtsev
, and
J.
Mendes
, “
Kuramoto model with frequency-degree correlations on complex networks
,”
Phys. Rev. E
87
,
032106
(
2013
).
28.
P. S.
Skardal
,
J.
Sun
,
D.
Taylor
, and
J. G.
Restrepo
, “
Effects of degree-frequency correlations on network synchronization: Universality and full phase-locking
,”
Europhys. Lett.
101
,
20001
(
2013
).
29.
P. S.
Skardal
,
D.
Taylor
, and
J.
Sun
, “
Optimal synchronization of complex networks
,”
Phys. Rev. Lett.
113
,
144101
(
2014
).
30.
P. S.
Skardal
,
D.
Taylor
, and
J.
Sun
, “
Optimal synchronization of directed complex networks
,”
Chaos
26
,
094807
(
2016
).
31.
D.
Taylor
,
P. S.
Skardal
, and
J.
Sun
, “
Synchronization of heterogeneous oscillators under network modifications: Perturbation and optimization of the synchrony alignment function
,”
SIAM J. Appl. Math.
76
,
1984
2008
(
2016
).
32.
I.
Klickstein
,
L.
Pecora
, and
F.
Sorrentino
, “
Symmetry induced group consensus
,”
Chaos
29
,
073101
(
2019
).
33.
Y.
Wang
,
L.
Wang
,
H.
Fan
, and
X.
Wang
, “
Cluster synchronization in networked nonidentical chaotic oscillators
,”
Chaos
29
,
093118
(
2019
).
34.
A.
Salova
,
J.
Emenheiser
,
A.
Rupe
,
J. P.
Crutchfield
, and
R. M.
D’Souza
, “
Koopman operator and its approximations for systems with symmetries
,”
Chaos
29
,
093128
(
2019
).
35.
M.
Sebek
and
I. Z.
Kiss
, “
Plasticity facilitates pattern selection of networks of chemical oscillations
,”
Chaos
29
,
083117
(
2019
).
36.
R.
Berner
,
J.
Fialkowski
,
D.
Kasatkin
,
V.
Nekorkin
,
S.
Yanchuk
, and
E.
Schöll
, “
Hierarchical frequency clusters in adaptive networks of phase oscillators
,”
Chaos
29
,
103134
(
2019
).
37.
S.
Faci-Lázaro
,
J.
Soriano
, and
J.
Gómez-Gardeñes
, “
Impact of targeted attack on the spontaneous activity in spatial and biologically-inspired neuronal networks
,”
Chaos
29
,
083126
(
2019
).
38.
L.
Arola-Fernández
,
G.
Mosquera-Doñate
,
B.
Steinegger
, and
A.
Arenas
, “
Uncertainty propagation in complex networks: From noisy links to critical properties
,”
Chaos
30
,
023129
(
2020
).
39.
X.
Lei
,
W.
Liu
,
W.
Zou
, and
J.
Kurths
, “
Coexistence of oscillation and quenching states: Effect of low-pass active filtering in coupled oscillators
,”
Chaos
29
,
073110
(
2019
).
40.
J. D.
Johnson
and
D. M.
Abrams
, “
A coupled oscillator model for the origin of bimodality and multimodality
,”
Chaos
29
,
073120
(
2019
).
41.
S. R.
Huddy
, “
Using critical curves to compute master stability islands for amplitude death in networks of delay-coupled oscillators
,”
Chaos
30
,
013118
(
2020
).
42.
K.
Daley
,
K.
Zhao
, and
I. V.
Belykh
, “
Synchronizability of directed networks: The power of non-existent ties
,”
Chaos
30
,
043102
(
2020
).
43.
J. S.
Climaco
and
A.
Saa
, “
Optimal global synchronization of partially forced Kuramoto oscillators
,”
Chaos
29
,
073115
(
2019
).
44.
L.
Chen
,
P.
Ji
,
D.
Waxman
,
W.
Lin
, and
J.
Kurths
, “
Effects of dynamical and structural modifications on synchronization
,”
Chaos
29
,
083131
(
2019
).
You do not currently have access to this content.