Lie Operad
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In mathematics, the Lie operad is an
operad In mathematics, an operad is a structure that consists of abstract operations, each one having a fixed finite number of inputs (arguments) and one output, as well as a specification of how to compose these operations. Given an operad O, one define ...
whose algebras are
Lie algebra In mathematics, a Lie algebra (pronounced ) is a vector space \mathfrak g together with an Binary operation, operation called the Lie bracket, an Alternating multilinear map, alternating bilinear map \mathfrak g \times \mathfrak g \rightarrow ...
s. The notion (at least one version) was introduced by in their formulation of
Koszul duality In mathematics, Koszul duality, named after the French mathematician Jean-Louis Koszul, is any of various kinds of dualities found in representation theory of Lie algebras, abstract algebras (semisimple algebra) and topology (e.g., equivariant cohom ...
.


Definition à la Ginzburg–Kapranov

Fix a base field ''k'' and let \mathcal(x_1, \dots, x_n) denote the
free Lie algebra In mathematics, a free Lie algebra over a field ''K'' is a Lie algebra generated by a set ''X'', without any imposed relations other than the defining relations of alternating ''K''-bilinearity and the Jacobi identity. Definition The definition ...
over ''k'' with generators x_1, \dots, x_n and \mathcal(n) \subset \mathcal(x_1, \dots, x_n) the subspace spanned by all the bracket monomials containing each x_i exactly once. The
symmetric group In abstract algebra, the symmetric group defined over any set is the group whose elements are all the bijections from the set to itself, and whose group operation is the composition of functions. In particular, the finite symmetric group \m ...
S_n acts on \mathcal(x_1, \dots, x_n) by permutations of the generators and, under that action, \mathcal(n) is invariant. The operadic composition is given by substituting expressions (with renumbered variables) for variables. Then, \mathcal = \ is an operad.


Koszul-Dual

The
Koszul-dual In mathematics, Koszul duality, named after the French mathematician Jean-Louis Koszul, is any of various kinds of dualities found in representation theory of Lie algebras, abstract algebras (semisimple algebra) and topology (e.g., equivariant cohom ...
of \mathcal is the
commutative-ring operad In mathematics, an operad is a structure that consists of abstract operations, each one having a fixed finite number of inputs (arguments) and one output, as well as a specification of how to compose these operations. Given an operad O, one define ...
, an operad whose algebras are the commutative rings over ''k.''


Notes


References

*


External links

*Todd Trimble
Notes on operads and the Lie operad
*https://ncatlab.org/nlab/show/Lie+operad Algebra {{algebra-stub