Quiz:Element structure of symmetric group:S3

See element structure of symmetric group:S3 for full details.

Element orders and conjugacy class structure

Review the conjugacy class structure: [SHOW MORE]

Partition	Partition in grouped form	Verbal description of cycle type	Elements with the cycle type in cycle decomposition notation	Elements with the cycle type in one-line notation	Size of conjugacy class	Formula for size	Even or odd? If even, splits? If splits, real in alternating group?	Element order	Formula calculating element order
1 + 1 + 1	1 (3 times)	three fixed points	$()$ -- the identity element	123	1	$\! \frac{3!}{(1)^3(3!)}$	even; no	1	$\operatorname{lcm} \{ 1, 1, 1 \}$
2 + 1	2 (1 time), 1 (1 time)	transposition in symmetric group:S3: one 2-cycle, one fixed point	$(1,2)$, $(1,3)$, $(2,3)$	213, 321, 132	3	$\! \frac{3!}{(2)(1)}$	odd	2	$\operatorname{lcm} \{ 2,1 \}$
3	3 (1 time)	3-cycle in symmetric group:S3: one 3-cycle	$(1,2,3)$, $(1,3,2)$	231, 312	2	$\! \frac{3!}{3}$	even; yes; no	3	$\operatorname{lcm} \{ 3 \}$
Total (3 rows -- 3 being the number of unordered integer partitions of 3)	--	--	--	--	6 (equals 3!, the size of the symmetric group)	--	odd: 3 even;no: 1 even; yes; no: 2	order 1: 1, order 2: 3, order 3: 2	--

1 What is the number of non-identity elements of the symmetric group of degree three?

	2
	3
	4
	5
	6

2 How many elements are there of order exactly three in the symmetric group of degree three?

	2
	3
	4
	5
	6

3 Which of the following is a correct description of the conjugacy class structure of the symmetric group of degree three?

	Conjugacy class of size 1 and order (of elements in the conjugacy class) 1, conjugacy class of size 2 and order (of elements in the conjugacy class) 2, conjugacy class of size 3 and order (of elements in the conjugacy class) 3
	Conjugacy class of size 1 and order (of elements in the conjugacy class) 1, conjugacy class of size 2 and order (of elements in the conjugacy class) 3, conjugacy class of size 3 and order (of elements in the conjugacy class) 2
	Conjugacy class of size 1 and order (of elements in the conjugacy class) 2, conjugacy class of size 2 and order (of elements in the conjugacy class) 1, conjugacy class of size 3 and order (of elements in the conjugacy class) 3
	Conjugacy class of size 1 and order (of elements in the conjugacy class) 2, conjugacy class of size 2 and order (of elements in the conjugacy class) 3, conjugacy class of size 3 and order (of elements in the conjugacy class) 1
	Conjugacy class of size 1 and order (of elements in the conjugacy class) 3, conjugacy class of size 2 and order (of elements in the conjugacy class) 1, conjugacy class of size 3 and order (of elements in the conjugacy class) 2
	Conjugacy class of size 1 and order (of elements in the conjugacy class) 3, conjugacy class of size 2 and order (of elements in the conjugacy class) 2, conjugacy class of size 3 and order (of elements in the conjugacy class) 1

Multiplication, conjugacy and generating sets

Review the multiplication table in cycle decomposition notation: [SHOW MORE]

Element	$()$	$(1, 2)$	$(2, 3)$	$(1, 3)$	$(1, 2, 3)$	$(1, 3, 2)$
$()$	$()$	$(1, 2)$	$(2, 3)$	$(1, 3)$	$(1, 2, 3)$	$(1, 3, 2)$
$(1, 2)$	$(1, 2)$	$()$	$(1, 2, 3)$	$(1, 3, 2)$	$(2, 3)$	$(1, 3)$
$(2, 3)$	$(2, 3)$	$(1, 3, 2)$	$()$	$(1, 2, 3)$	$(1, 3)$	$(1, 2)$
$(1, 3)$	$(1, 3)$	$(1, 2, 3)$	$(1, 3, 2)$	$()$	$(1, 2)$	$(2, 3)$
$(1, 2, 3)$	$(1, 2, 3)$	$(1, 3)$	$(1, 2)$	$(2, 3)$	$(1, 3, 2)$	$()$
$(1, 3, 2)$	$(1, 3, 2)$	$(2, 3)$	$(1, 3)$	$(1, 2)$	$()$	$(1, 2, 3)$

Review the multiplication table in one-line notation: [SHOW MORE]

Element	123	213	132	321	231	312
123	123	213	132	321	231	312
213	213	123	231	312	132	321
132	132	312	123	231	321	213
321	321	231	312	123	213	132
231	231	321	213	132	312	123
312	312	132	321	213	123	231

1 What can we say about the order of the product of two distinct elements, each of order exactly two, in the symmetric group of degree three?

	The product must be the identity element
	The product must have order two
	The product can have order either 1 or 2
	The product must have order three
	The product can have order either 1 or 3

2 What can we say about the order of the product of two distinct elements, each of order exactly three, in the symmetric group of degree three?

	The product must be the identity element
	The product must have order two
	The product can have order either 1 or 2
	The product must have order three
	The product can have order either 1 or 3

3 Which of the following is false in the symmetric group of degree three?

	Any two elements of the same order are conjugate
	Every element is conjugate to its inverse
	Any two elements generating the same cyclic subgroup are conjugate
	Any two elements that together generate the whole group are conjugate
	None of the above, i.e., they are all true

Conjugation and commutator operations

Review the conjugation operation: [SHOW MORE]

Review the commutator operation: [SHOW MORE]

Here, the two inputs are group elements $g,h$, and the output is the commutator. We first give the table assuming the left definition of commutator: $[g,h] = ghg^{-1}h^{-1}$. Here, the row element is $g$ and the column element is $h$. Note that $[g,h] = [h,g]^{-1}$:

	$()$	$(1,2)$	$(2,3)$	$(1,3)$	$(1,2,3)$	$(1,3,2)$
$()$	$()$	$()$	$()$	$()$	$()$	$()$
$(1,2)$	$()$	$()$	$(1,3,2)$	$(1,2,3)$	$(1,2,3)$	$(1,3,2)$
$(2,3)$	$()$	$(1,2,3)$	$()$	$(1,3,2)$	$(1,2,3)$	$(1,3,2)$
$(1,3)$	$()$	$(1,3,2)$	$(1,2,3)$	$()$	$(1,2,3)$	$(1,3,2)$
$(1,2,3)$	$()$	$(1,3,2)$	$(1,3,2)$	$(1,3,2)$	$()$	$()$
$(1,3,2)$	$()$	$(1,2,3)$	$(1,2,3)$	$(1,2,3)$	$()$	$()$

The corresponding table with the right definition: PLACEHOLDER FOR INFORMATION TO BE FILLED IN: [SHOW MORE]

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Here is the information on the number of times each element occurs as a commutator:

Conjugacy class (indexing partition)	Elements	Number of occurrences of each as commutator	Probability of each occurring as the commutator of elements picked uniformly at random	Total number of occurrences as commutator	Total probability	Explanation
1 + 1 + 1	$()$	18	1/2	18	1/2	See commuting fraction and its relationship with the number of conjugacy classes.
2 + 1	$(1,2), (2,3), (1,3)$	0	0	0	0	Not in the derived subgroup.
3	$(1,2,3), (1,3,2)$	9	1/4	18	1/2

1 Suppose $g$ and $h$ are distinct elements of order two in the symmetric group of order three. What can we say about $ghg^{-1}$ (this is a conjugate of $h$ by $g$)?

	It equals $g$
	It equals $h$
	It equals an element of order two that is neither $g$ nor $h$
	It is an element of order three
	It is the identity element

2 Suppose $g$ and $h$ are distinct elements of order two in the symmetric group of order three. What can we say about the commutator $ghg^{-1}h^{-1}$?

	It equals $g$
	It equals $h$
	It equals an element of order two that is neither $g$ nor $h$
	It is an element of order three
	It is the identity element

3 Suppose $g$ and $h$ are distinct elements of order three in the symmetric group of order three. What can we say about $ghg^{-1}$ (this is a conjugate of $h$ by $g$)?

	It equals $g$
	It equals $h$
	It equals an element of order two
	It is the identity element

4 Suppose $g$ and $h$ are distinct elements of order three in the symmetric group of order three. What can we say about the commutator $ghg^{-1}h^{-1}$?

	It equals $g$
	It equals $h$
	It is an element of order two
	It is the identity element

5 Suppose $g$ is an element of order two and $h$ is an element of order three in the symmetric group of order three. What are the orders of the elements $ghg^{-1}$ and $hgh^{-1}$ respectively?

	1 and 1
	2 and 3
	3 and 2
	2 and 2
	3 and 3