Subgroup
Definition
Let be a group with identity element . A subgroup of is a subset with these three properties. The identity is in . For all , the product is in . For each , the inverse is in . The notation means that is a subgroup of .
Remarks
A subgroup is a group with the operation of restricted to , and its identity is the identity of . Each group has the subgroups and . The even integers form a subgroup of . The natural numbers do not form a subgroup of , because is not a natural number.
Explanations
L1 human
A subgroup is a smaller group that lives inside a bigger group and uses the same operation. To check that a subset is a subgroup, you check that it contains the identity and that it is closed under products and inverses. For example, the rotations of a square form a subgroup of all the symmetries of the square.
What this node needs for W2
- edge instance_of in: one example (0 of 1)
- edge not_instance_of in: one non-example that fails one clause (0 of 1)
The writing levels say how complete the text of a node is. They do not measure its truth.
What this needs
To read this node, read these 2 nodes in this order. The foundations come first, and the list ends with this node.
- no evidence level
What depends on this
121 nodes use this node, directly or through other nodes.
- A finite group is nilpotent iff it is the product of its Sylow subgroups 00Y9N80VSS
- Image of a homomorphism 0112DTS464
- Semidirect product 014E1DZQE8
- Characteristic subgroup 01CS8Q2APC
- Normality via left and right cosets 01E7SWYJX3
- Extensions of solvable groups are solvable 01EY0EM7RP
- Quotients of solvable groups are solvable 027ZQS04SJ
- Infinite cyclic group 02B1T50JD1
- Order of a cyclic subgroup equals the order of its generator 031M8HX7DA
- Subgroups of a finite cyclic group correspond to divisors of its order 0423TXR9AN
- Order of a group is the index times the order of the subgroup 04DC0SRN2K
- Index of a subgroup 04QEBF8S49
- Cyclic groups are abelian 04RG02S6BA
- The dihedral group of order 8 054SBCQ93T
- Stabilisers of points in the same orbit are conjugate 05BM304NRX
- Left coset 05FD317V2W
- Inner automorphism group is isomorphic to G modulo its centre 05HYGWFG63
- Groups of prime order are cyclic 05MM4EK4SA
- Subgroup criterion 05N4TQKPH0
- Subgroups of solvable groups are solvable 05Y0F9M0TS
- Right coset 060Z37VVB6
- Classification of finite simple groups 06J6P03MG7
- Cyclic groups of the same order are isomorphic 0736AXH2ME
- Classification of finite abelian groups 07CQR9BW3R
- Finite p-groups are nilpotent 081WTKYX6C
- Class equation 08BPSC6YTE
- Product of cyclic groups is cyclic iff the orders are coprime 08FDFEF8D1
- Fixed points of an action 08JF1K4DW1
- Lower central series 08PA437800
- Product formula for the order of HK 08PY4GNAPK
- Commutator subgroup 08SJ5K2CBG
- Order of an element divides the order of the group 08V7JHS3QZ
- Subnormal series 096HN851YZ
- Fixed points of a p-group action 098D2E7DEH
- Second Sylow theorem 09GCQ5STVJ
- Dihedral group 09GK3DE0WV
- The symmetric group S3 09H9Y0Q11W
- Outer automorphism group 09HEXDQ0CQ
- Groups of order p squared are abelian 09JZ9P4899
- The number of Sylow subgroups is the index of the normaliser 09ZJ6CAK7S
- If G modulo its centre is cyclic then G is abelian 0AH9Q6YNMT
- The symmetric group is generated by transpositions 0AQNX7G443
- Simplicity of the alternating group 0ARPRJQWZ2
- Normaliser 0AT1ZSNM25
- Action on left cosets 0AZG100DKH
- Cyclic group 0B85Q41RP6
- Lattice of subgroups 0B8BW4YWTF
- Order of the dihedral group 0BZVNWJ352
- Simple group 0C093D1T4M
- The kernel is a normal subgroup 0C9ZKYSPYR
- First isomorphism theorem 0CXXJNG5B6
- Conjugate subgroup 0D6WHTTH7T
- Upper central series 0DJ9Y9V610
- Cosets have the same cardinality as the subgroup 0DKMBWTD7P
- Nilpotent group 0DZPD2MG33
- Jordan–Hölder theorem 0E088ZP533
- Orbit-stabiliser theorem 0E2HSCKZ6C
- Universal property of the abelianisation 0EJ4PC8NJ6
- A subgroup whose index is the smallest prime divisor of the order is normal 0FEBE9NC0E
- Burnside's p^a q^b theorem 0FMAQSB1SC
- Cyclic group of order n 0G0B3DRG65
- Automorphism group of a cyclic group 0G4C8SJ6PV
- Universal property of the quotient group 0GJ83E78A5
- The alternating group A5 is simple 0GKQKF0FXJ
- Nilpotent groups are solvable 0GNG2KVPZJ
- Abelianisation 0H9K5D3RDV
- Finitely generated group 0HY15D6WTX
- The symmetric group on five or more letters is not solvable 0J53NE674D
- Abelian simple groups have prime order 0JJV80RXHD
- Cauchy's theorem 0JM7PA288B
- Subgroups of abelian groups are normal 0JPDTEDCFD
- Sylow p-subgroup 0JWZX6FKSH
- Subgroups of cyclic groups are cyclic 0KB1ND7XDS
- The alternating group is generated by three-cycles 0KFZ0QX83G
- The number of Sylow subgroups divides the index 0M3PYJ3TSE
- Generators of a group 0MBV2VHMXA
- A finite abelian group is cyclic iff its exponent equals its order 0MC0AQZSHE
- A quotient is abelian iff the subgroup contains the commutator subgroup 0MS8QGA6S5
- Composition series 0NB8VPB93V
- Product of two subgroups 0NS1YTGM19
- Solvable group 0P3KZK0FTV
- Action by conjugation 0P8CY9V437
- Second isomorphism theorem 0PPP2J2DJV
- Centraliser 0Q0Z1BEXTF
- Internal direct product 0Q2MVQ7JMT
- Third Sylow theorem 0Q8DGAZSJ4
- Von Dyck's theorem 0QPYHHNRXC
- The group of units of Z/pZ is cyclic 0QTHB6PE52
- Frattini argument 0QTZDKJEDV
- Presentation of a group 0QZCY9PE3Q
- Abelian groups are solvable 0R0X73XHAT
- Derived series 0R3H35G96G
- Composition factors 0RFP7F3SEW
- Subgroup generated by a subset 0RG9SPQSWM
- Stabiliser 0RGGF8ZS6D
- Torsion subgroup 0RH1TPDGCQ
- Structure theorem for finitely generated abelian groups 0RY0B72XAS
- A nontrivial finite p-group has nontrivial centre 0RZCTT30H5
- Size of an orbit times the size of the stabiliser 0S19CWFZM2
- Correspondence theorem 0S9ZVZ34MD
- Subgroups of the integers 0SRATCFF1W
- Characteristic subgroups are normal 0SRE7K4E49
- Order of the alternating group 0SZ1KMNWVE
- Normal core 0T0KMZPYV9
- Third isomorphism theorem 0TJ1V9DDPC
- Product of a subgroup and a normal subgroup is a subgroup 0TXWV1JGG1
- Subgroups of index two are normal 0V547YQRMV
- First Sylow theorem 0V98WY94B8
- Size of a conjugacy class is the index of the centraliser 0VK5V9P8G3
- Normal subgroup 0W77CVBCHQ
- Number of elements of each order in a cyclic group 0XCYGCCX8V
- Groups of order pq 0YBR6QPY4Y
- Cayley graph 0YE597NHGB
- Integers modulo n as a quotient group 0YJ3WRR9RY
- Free abelian group 0YMSEZE1VH
- Cyclic subgroup generated by an element 0YT586TKXF
- Quotient group 0YYWCNTPWR
- Burnside's lemma 0Z47M1B2VS
- g to the order of the group is the identity 0ZEPNS9BXK
- Tower law for indices 0ZQJ7KEFQ5
- Intersection of subgroups is a subgroup 0ZTGMDNVTB
Sources
- Web https://en.wikipedia.org/wiki/Subgroup, lead section
- Web https://en.wikipedia.org/wiki/Subgroup, Basic properties of subgroups
What links here
Used by
- Image of a homomorphism 0112DTS464
- Characteristic subgroup 01CS8Q2APC
- Left coset 05FD317V2W
- Subgroup criterion 05N4TQKPH0
- Subgroups of solvable groups are solvable 05Y0F9M0TS
- Right coset 060Z37VVB6
- Normaliser 0AT1ZSNM25
- Lattice of subgroups 0B8BW4YWTF
- Conjugate subgroup 0D6WHTTH7T
- Sylow p-subgroup 0JWZX6FKSH
- Subgroups of cyclic groups are cyclic 0KB1ND7XDS
- Product of two subgroups 0NS1YTGM19
- Centraliser 0Q0Z1BEXTF
- Subgroup generated by a subset 0RG9SPQSWM
- Stabiliser 0RGGF8ZS6D
- Torsion subgroup 0RH1TPDGCQ
- Normal subgroup 0W77CVBCHQ
- Cyclic subgroup generated by an element 0YT586TKXF
- Intersection of subgroups is a subgroup 0ZTGMDNVTB