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2 Lie algebras and breadth
 2.1 Attributes
 2.2 Breadth
 2.3 Inflation of Lie algebras

2 Lie algebras and breadth

2.1 Attributes

2.1-1 LieClass
‣ LieClass( L )( attribute )

Computes the class of the nilpotent Lie algebra \(L\).

2.1-2 LieType
‣ LieType( L )( attribute )

Computes the type of the nilpotent Lie algebra \(L\).

2.1-3 IsOfMaximalClass
‣ IsOfMaximalClass( L )( property )

Returns: true or false

Returns whether the nilpotent Lie algebra \(L\) is of maximal class or not.

2.1-4 StructureMatrices
‣ StructureMatrices( L )( attribute )

Computes the structure matrices of the nilpotent Lie algebra \(L\).

2.1-5 BasisLieCenter
‣ BasisLieCenter( L )( attribute )

Returns the elements of the basis Lie algebra \(L\) that are contained in the center of \(L\).

2.1-6 BasisLieDerived
‣ BasisLieDerived( L )( attribute )

Returns the elements of the basis Lie algebra \(L\) that are contained in the derived subalgebra of \(L\).

2.1-7 LieAdjointMatrix
‣ LieAdjointMatrix( L )( attribute )

Computes the adjoint matrix of the Lie algebra \(L\).

2.1-8 PrintLiePresentation
‣ PrintLiePresentation( L )( attribute )

Prints the Lie presentation of the Lie algebra \(L\).

2.2 Breadth

2.2-1 InfoLieBreadth
‣ InfoLieBreadth( info class )

Info class for the functions of the breadth of Lie algebras.

2.2-2 LieBreadth
‣ LieBreadth( L )( attribute )

Computes the breadth of the Lie algebra \(L\).

2.2-3 IsTrueClassBreadth
‣ IsTrueClassBreadth( L )( property )

Returns: true or false

Returns whether the Lie algebra \(L\) holds the class-breadth conjecture or not.

2.2-4 TGroupBreadth
‣ TGroupBreadth( G )( function )

Computes the breadth of the T-groupo \(G\).

2.3 Inflation of Lie algebras

A grading for a Lie algebra \(L\) is a decomposition L = \(\bigoplus_{i=1}^n L_i\) that respects the Lie bracket, i.e. \([L_i,L_j]\subseteq L_{i+j}\).}. Any nilpotent Lie algebras can be graded by taking \(L_i = \gamma_i(L)/\gamma_{i+1}(L)\). Let \(L\) be a nilpotent Lie algebra of maximal class. The two-step centralizers are the sets \(C_i = C_{L_1}(L_i) = \{x \in L_1 \mid [x,L_i] = 0 \}\) for all \(2\leq i \leq c\). Let \(\mathcal{C}=\{C_i\}\setminus L_1\), we say that a Lie algebra of maximal class is covered if the set \(\mathcal{C}\) consist of all one-dimensional subspaces of \(L_1\).

Let \(L\) be a graded Lie algebra \(L = \bigoplus_{i=1}^n L_i\) over \(K=\F_q\) for some prime power \(q=p^n\). Consider the field extension \(A=K[\varepsilon]/\langle \varepsilon^p \rangle\) which is a vector space over \(K\) of dimension \(p\). The algebra \(A\) is an associative, commutative and has a unit. The algebra \(L\otimes A\) over \(K\) defined by \([x\otimes a, y\otimes b] = [x,y]\otimes ab\) is a graded Lie algebra. Let \(M\) be a maximal ideal of \(L\) and consider the Lie subalgebra \(M^\uparrow = M\otimes A\). Let \(D\) be a derivation of \(L\) of degree 1. Define \(D^\uparrow\) via: \(D^\uparrow(x\otimes \varepsilon^i)=D(x)\otimes \varepsilon^i\), this is a derivation of \(M^\uparrow\) of degree 1. Define the derivation \(E\in \Der M^\uparrow\) by \(E(x\otimes \varepsilon^i) = D^\uparrow(x\otimes\varepsilon^i\cdot\varepsilon^{p-1})+1\otimes\partial_\varepsilon(\varepsilon^i)\). Let \(s\in L_1\setminus M\), take \(D=\mathrm{ad}_s\), and extend it naturally to \(M^\uparrow\). Denote \(E_{s^\prime}\) as previously. The inflation \({}^{M}L\) of \(L\) at \(M\) by \(s\in L_1\setminus M\) is the graded Lie algebra obtained as an extension of \(M^\uparrow\) by an element \(s^\prime\), which is the extension of \(s\) that induces the derivation \(E_{s^\prime}\), that is,

\[ [x\otimes a, s^\prime] = E_{s^\prime}(x\otimes a) = \mathrm{ad}_{s^\prime}(x\otimes\varepsilon^i)+x\otimes\partial_\varepsilon(\varepsilon^i). \]

2.3-1 InfoInflation
‣ InfoInflation( info class )

Info class for the functions of the inflation of Lie algebras.

2.3-2 LieNilpotentGrading
‣ LieNilpotentGrading( L )( attribute )

Computes a grading of the nilpotent Lie algebra \(L\) using the lower central series.

2.3-3 LieTwoStepCentralizers
‣ LieTwoStepCentralizers( L )( attribute )

Computes the two step centralizers of the Lie algebra \(L\).

2.3-4 IsLieCovered
‣ IsLieCovered( L )( property )

Returns: true or false

Returns whether the Lie algebra \(L\) is covered or not.

2.3-5 PolynomialAlgebra
‣ PolynomialAlgebra( F )( attribute )

For a finite field \(F\) computes the polynomial algebra \(F[x]\).

2.3-6 LieCoveredInflated
‣ LieCoveredInflated( n )( attribute )

For \(n=2,3,4\) computes the covered Lie algebras of maximal class using the polynomial algebra of dimension \(n\). For n=3 one can directly load the Lie algebra by reading the file "inflation_3.g".

2.3-7 LieMinimalQuotientClassBreadth
‣ LieMinimalQuotientClassBreadth( L )( attribute )

Given a covered Lie algebras of maximal class \(L\) computes the minimal quotient that not holds the class-breadth conjecture.

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