Basic lemmas about semigroups, monoids, and groups #
This file lists various basic lemmas about semigroups, monoids, and groups. Most proofs are
one-liners from the corresponding axioms. For the definitions of semigroups, monoids and groups, see
algebra/group/defs.lean
.
Composing two associative operations of f : α → α → α
on the left
is equal to an associative operation on the left.
Composing two associative operations of f : α → α → α
on the right
is equal to an associative operation on the right.
Composing two additions on the left by y
then x
is equal to a addition on the left by x + y
.
Composing two multiplications on the left by y
then x
is equal to a multiplication on the left by x * y
.
Composing two additions on the right by y
and x
is equal to a addition on the right by y + x
.
Alias of the reverse direction of div_eq_one
.
Alias of the reverse direction of sub_eq_zero
.
The commutator of two elements g₁
and g₂
.
Order dual #
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Lexicographical order #
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- lex.has_one = h
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- lex.has_add = h
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- lex.has_mul = h
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- lex.has_inv = h
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- lex.has_neg = h
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- lex.has_div = h
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- lex.has_sub = h
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- lex.has_pow = h
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- lex.monoid = h