Table of Lie groups

Column legend

• Cpt: Is this group G compact? (Yes or No)
• ${\displaystyle \pi _{0}}$: Gives the group of components of G. The order of the component group gives the number of connected components. The group is connected if and only if the component group is trivial (denoted by 0).
• ${\displaystyle \pi _{1}}$: Gives the fundamental group of G whenever G is connected. The group is simply connected if and only if the fundamental group is trivial (denoted by 0).
• UC: If G is not simply connected, gives the universal cover of G.

Lie group	Description	Cpt	${\displaystyle \pi _{0}}$	${\displaystyle \pi _{1}}$	UC	Remarks	Lie algebra	dim/R
Rn	Euclidean space with addition	N	0	0		abelian	Rn	n
R×	nonzero real numbers with multiplication	N	Z2	–		abelian	R	1
R+	positive real numbers with multiplication	N	0	0		abelian	R	1
S1 = U(1)	the circle group: complex numbers of absolute value 1 with multiplication;	Y	0	Z	R	abelian, isomorphic to SO(2), Spin(2), and R/Z	R	1
Aff(1)	invertible affine transformations from R to R.	N	Z2	0		solvable, semidirect product of R+ and R×	${\displaystyle \left\{\left[{\begin{smallmatrix}a&b\\0&0\end{smallmatrix}}\right]:a,b\in \mathbb {R} \right\}}$	2
H×	non-zero quaternions with multiplication	N	0	0			H	4
S3 = Sp(1)	quaternions of absolute value 1 with multiplication; topologically a 3-sphere	Y	0	0		isomorphic to SU(2) and to Spin(3); double cover of SO(3)	Im(H)	3
GL(n,R)	general linear group: invertible n×n real matrices	N	Z2	–			M(n,R)	n2
GL+(n,R)	n×n real matrices with positive determinant	N	0	Z  n=2 Z2 n>2		GL+(1,R) is isomorphic to R+ and is simply connected	M(n,R)	n2
SL(n,R)	special linear group: real matrices with determinant 1	N	0	Z  n=2 Z2 n>2		SL(1,R) is a single point and therefore compact and simply connected	sl(n,R)	n2−1
SL(2,R)	Orientation-preserving isometries of the Poincaré half-plane, isomorphic to SU(1,1), isomorphic to Sp(2,R).	N	0	Z		The universal cover has no finite-dimensional faithful representations.	sl(2,R)	3
O(n)	orthogonal group: real orthogonal matrices	Y	Z2	–		The symmetry group of the sphere (n=3) or hypersphere.	so(n)	n(n−1)/2
SO(n)	special orthogonal group: real orthogonal matrices with determinant 1	Y	0	Z  n=2 Z2 n>2	Spin(n) n>2	SO(1) is a single point and SO(2) is isomorphic to the circle group, SO(3) is the rotation group of the sphere.	so(n)	n(n−1)/2
Spin(n)	spin group: double cover of SO(n)	Y	0 n>1	0 n>2		Spin(1) is isomorphic to Z2 and not connected; Spin(2) is isomorphic to the circle group and not simply connected	so(n)	n(n−1)/2
Sp(2n,R)	symplectic group: real symplectic matrices	N	0	Z			sp(2n,R)	n(2n+1)
Sp(n)	compact symplectic group: quaternionic n×n unitary matrices	Y	0	0			sp(n)	n(2n+1)
Mp(2n,R)	metaplectic group: double cover of real symplectic group Sp(2n,R)	Y	0	Z		Mp(2,R) is a Lie group that is not algebraic	sp(2n,R)	n(2n+1)
U(n)	unitary group: complex n×n unitary matrices	Y	0	Z	R×SU(n)	For n=1: isomorphic to S1. Note: this is not a complex Lie group/algebra	u(n)	n2
SU(n)	special unitary group: complex n×n unitary matrices with determinant 1	Y	0	0		Note: this is not a complex Lie group/algebra	su(n)	n2−1

Table legend:

• S: Is this algebra simple? (Yes or No)
• SS: Is this algebra semi-simple? (Yes or No)

The dimensions given are dimensions over C. Note that every complex Lie group/algebra can also be viewed as a real Lie group/algebra of twice the dimension.

Lie group	Description	Cpt	${\displaystyle \pi _{0}}$	${\displaystyle \pi _{1}}$	UC	Remarks	Lie algebra	dim/C
Cn	group operation is addition	N	0	0		abelian	Cn	n
C×	nonzero complex numbers with multiplication	N	0	Z		abelian	C	1
GL(n,C)	general linear group: invertible n×n complex matrices	N	0	Z		For n=1: isomorphic to C×	M(n,C)	n2
SL(n,C)	special linear group: complex matrices with determinant 1	N	0	0		for n=1 this is a single point and thus compact.	sl(n,C)	n2−1
SL(2,C)	Special case of SL(n,C) for n=2	N	0	0		Isomorphic to Spin(3,C), isomorphic to Sp(2,C)	sl(2,C)	3
PSL(2,C)	Projective special linear group	N	0	Z2	SL(2,C)	Isomorphic to the Möbius group, isomorphic to the restricted Lorentz group SO+(3,1,R), isomorphic to SO(3,C).	sl(2,C)	3
O(n,C)	orthogonal group: complex orthogonal matrices	N	Z2	–		compact for n=1	so(n,C)	n(n−1)/2
SO(n,C)	special orthogonal group: complex orthogonal matrices with determinant 1	N	0	Z  n=2 Z2 n>2		SO(2,C) is abelian and isomorphic to C×; nonabelian for n>2. SO(1,C) is a single point and thus compact and simply connected	so(n,C)	n(n−1)/2
Sp(2n,C)	symplectic group: complex symplectic matrices	N	0	0			sp(2n,C)	n(2n+1)

The dimensions given are dimensions over C. Note that every complex Lie algebra can also be viewed as a real Lie algebra of twice the dimension.

Lie algebra	Description	S	SS	Remarks	dim/C
C	the complex numbers				1
Cn	the Lie bracket is zero				n
M(n,C)	n×n matrices with Lie bracket the commutator				n2
sl(n,C)	square matrices with trace 0 with Lie bracket the commutator	Y	Y		n2−1
sl(2,C)	Special case of sl(n,C) with n=2	Y	Y	isomorphic to su(2) ${\displaystyle \otimes }$ C	3
so(n,C)	skew-symmetric square complex matrices with Lie bracket the commutator	Y	Y	Exception: so(4,C) is semi-simple, but not simple.	n(n−1)/2
sp(2n,C)	complex matrices that satisfy JA + ATJ = 0 where J is the standard skew-symmetric matrix	Y	Y		n(2n+1)

The Lie algebra of affine transformations of dimension two, in fact, exist for any field. An instance has already been listed in the first table for real Lie algebras.

• Fulton, William; Harris, Joe (1991). Representation theory. A first course. Graduate Texts in Mathematics, Readings in Mathematics. 129. New York: Springer-Verlag. doi:10.1007/978-1-4612-0979-9. ISBN 978-0-387-97495-8. MR 1153249. OCLC 246650103.