What is the Dimension of Lie Algebras \mathfrak{g} and \mathfrak{h}?

In summary, \mathfrak{g} and \mathfrak{h} are both Lie algebras, with \mathfrak{g} having basis vectors E,F,G satisfying specific relations for Lie brackets, and \mathfrak{h} consisting of 3x3 matrices with a specific form and operations. The dimension of both Lie algebras is 3.
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Homework Statement



[itex]\mathfrak{g}[/itex] is the Lie algebra with basis vectors [itex]E,F,G[/itex] such that the following relations for Lie brackets are satisfied:

[itex][E,F]=G,\;\;[E,G]=0,\;\;[F,G]=0.[/itex]

[itex]\mathfrak{h}[/itex] is the Lie algebra consisting of 3x3 matrices of the form

[itex]\begin{bmatrix} 0 & a & c \\ 0 & 0 & b \\ 0 & 0 & 0 \end{bmatrix}[/itex] where [itex]a,b,c[/itex] are any complex numbers. The vector addition and scalar multiplication on [itex]\mathfrak{h}[/itex] are the usual operations on matrices.

The Lie bracket on [itex]\mathfrak{h}[/itex] is defined as the matrix commutator: [itex][X,Y] = XY - YX[/itex] for any [itex]X,Y \in \mathfrak{h}.[/itex]

The Attempt at a Solution



Is the dimension of [itex]\mathfrak{g}[/itex] and [itex]\mathfrak{h}[/itex] both 3?
 
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  • #2
Yes, the dimension of \mathfrak{g} and \mathfrak{h} are both 3. This is because they each have three basis vectors or matrices, respectively.
 

1. What is the definition of Lie algebra dimension?

Lie algebra dimension is the number of independent generators or basis elements that are needed to describe the algebraic structure of a Lie algebra. It is a fundamental property of a Lie algebra that determines its size and complexity.

2. How is Lie algebra dimension related to the dimension of the underlying vector space?

The Lie algebra dimension is always equal to the dimension of the underlying vector space. This is because a Lie algebra is a vector space equipped with a specific type of algebraic structure, and the dimension of a vector space is defined as the number of linearly independent vectors that span it.

3. Can the dimension of a Lie algebra be infinite?

Yes, the dimension of a Lie algebra can be infinite. This occurs when the underlying vector space is infinite-dimensional, which is the case for certain types of Lie algebras, such as the Virasoro algebra.

4. How is the dimension of a Lie algebra calculated?

The dimension of a Lie algebra can be calculated by counting the number of independent generators or basis elements that satisfy the defining commutation relations of the algebra. This is typically done by finding a basis for the algebra and then determining the number of elements in the basis.

5. Does the dimension of a Lie algebra affect its properties?

Yes, the dimension of a Lie algebra can have a significant impact on its properties. For example, the dimension can determine whether the algebra is solvable or not, and it can also affect the classification and structure of the algebra. In general, higher dimensional Lie algebras tend to be more complex and have a wider range of possible properties.

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