maths.free › Abstract Algebra › Cyclic groups and permutation groups

Cyclic groups and permutation groups

Generators, orders, cycles, transpositions, parity.

A cyclic group is generated by one element; every permutation is a product of disjoint cycles, and its parity (even/odd) is well defined. Picture it: shuffling 5 cards as arrows between positions; a cycle is a loop of arrows. Think it: Cayley's theorem, every group is a permutation group, means permutations are the universal example.

Exemplo resolvido · inverse of 5 mod 12

Number-Theory · Modular-Arithmetic

Inverse of 5 mod 12

5,\ 12

Passo a passo

  1. 5x \equiv 1 \pmod{12}

    We want x with a·x ≡ 1 (mod m). It exists only when gcd(a, m) = 1.

  2. 12 = 2 \times 5 + 2

    Euclid step.

  3. 5 = 2 \times 2 + 1

    Euclid step.

  4. 2 = 2 \times 1 + 0

    Euclid step.

  5. 5 \times 5 = 25 \equiv 1 \pmod{12}

    Back-substitute (extended Euclid) to express 1 as a combination of a and m; the coefficient of a is the inverse.

Revelar a resposta
5^{-1} \equiv 5 \pmod{12}

Agora tu Escolha um problema, ou digite ou desenhe o seu próprio. Cada passo, uma imagem, a resposta escondida até que você pergunte.

Guarde o seu próprio trabalho

Uma conta gratuita adiciona notas sobre cada lição, um registro do que você terminou, seus problemas resolvidos em um lugar, e um tutor que você pode perguntar sobre esta página. A própria matemática está aberta a todos, assinada ou não.

Inscrever-se Login

Símbolos usados aqui

Toque em qualquer símbolo para a definição completa, uma imagem e o que cada letra nela significa.

Como: Cyclic groups and permutation groups

  1. We want x with a·x ≡ 1 (mod m). It exists only when gcd(a, m) = 1.
  2. Euclid step.
  3. Euclid step.
  4. Euclid step.
  5. Back-substitute (extended Euclid) to express 1 as a combination of a and m; the coefficient of a is the inverse.

Perguntas que as pessoas fazem

What is a group, in plain words?

A set with one operation that is associative, has an identity, and lets every element be undone. Symmetries of any object form a group. That is where the idea came from.

What is the difference between a ring and a field?

A ring has addition and multiplication that behave like the integers (you cannot always divide); a field is a ring where every non-zero element has a reciprocal, like the rationals or the reals.

Mais em Abstract Algebra

GroupsSubgroups, cosets and Lagrange's theoremHomomorphisms, normal subgroups and quotient groupsRings and fieldsGalois theory: why the quintic has no formula