Group Actions and Symmetry
This quiz covers fundamental concepts of group actions, including orbits, stabilizers, and the orbit-stabilizer theorem, as well as important symmetry groups such as permutation groups, dihedral groups, and polyhedral groups.
Questions
What is a group action?
- A mapping from a group to a set
- A transformation of a set by a group
- A group of transformations of a set
- A set of transformations that preserve a given structure
What is the orbit of an element under a group action?
- The set of all elements that are transformed into the given element
- The set of all elements that transform the given element into itself
- The set of all elements that commute with the given element
- The set of all elements that are fixed by the given element
What is the stabilizer of an element under a group action?
- The set of all elements that are transformed into the given element
- The set of all elements that transform the given element into itself
- The set of all elements that commute with the given element
- The set of all elements that are fixed by the given element
What is the kernel of a group action?
- The set of all elements that are transformed into the identity element
- The set of all elements that transform the identity element into itself
- The set of all elements that commute with the identity element
- The set of all elements that are fixed by the identity element
What is the fixed point set of a group action?
- The set of all elements that are transformed into themselves
- The set of all elements that transform themselves into themselves
- The set of all elements that commute with themselves
- The set of all elements that are fixed by themselves
What is the isotropy subgroup of an element under a group action?
- The set of all elements that are transformed into the given element
- The set of all elements that transform the given element into itself
- The set of all elements that commute with the given element
- The set of all elements that are fixed by the given element
What is the orbit-stabilizer theorem?
- The order of the orbit of an element is equal to the index of the stabilizer of the element
- The order of the stabilizer of an element is equal to the index of the orbit of the element
- The order of the orbit of an element is equal to the order of the stabilizer of the element
- The order of the stabilizer of an element is equal to the order of the orbit of the element
What is a transitive group action?
- A group action in which every element of the set is transformed into every other element
- A group action in which every element of the set is transformed into itself
- A group action in which every element of the set is transformed into a unique element
- A group action in which every element of the set is transformed into a finite number of elements
What is a regular group action?
- A transitive group action in which the stabilizer of every element is trivial
- A transitive group action in which the stabilizer of every element is finite
- A transitive group action in which the stabilizer of every element is infinite
- A transitive group action in which the stabilizer of every element is non-trivial
What is a permutation group?
- A group of transformations of a set
- A group of transformations of a set that preserves a given structure
- A group of transformations of a set that is transitive
- A group of transformations of a set that is regular
What is a symmetric group?
- A permutation group that is transitive
- A permutation group that is regular
- A permutation group that is both transitive and regular
- A permutation group that is neither transitive nor regular
What is the alternating group?
- The subgroup of the symmetric group consisting of all even permutations
- The subgroup of the symmetric group consisting of all odd permutations
- The subgroup of the symmetric group consisting of all permutations that fix a given element
- The subgroup of the symmetric group consisting of all permutations that do not fix any element
What is the dihedral group?
- The group of symmetries of a regular polygon
- The group of symmetries of a regular polyhedron
- The group of symmetries of a sphere
- The group of symmetries of a cube
What is the octahedral group?
- The group of symmetries of a cube
- The group of symmetries of a regular octahedron
- The group of symmetries of a regular dodecahedron
- The group of symmetries of a regular icosahedron
What is the icosahedral group?
- The group of symmetries of a cube
- The group of symmetries of a regular octahedron
- The group of symmetries of a regular dodecahedron
- The group of symmetries of a regular icosahedron