Finding basis of 3x3 matrix space

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SUMMARY

The discussion focuses on finding a basis for the space of 3x3 matrices with zero row sums and zero column sums. The user identifies that each row must contain one 0, one 1, and one -1 in various permutations for the zero row sum condition. The solution involves expressing a general 3x3 matrix and applying the constraints of row sums equaling zero, leading to a dimensionality reduction from 9 to 6. This results in the identification of 6 basis matrices that satisfy the conditions.

PREREQUISITES
  • Understanding of linear algebra concepts, specifically matrix theory.
  • Familiarity with the properties of matrix dimensions and basis vectors.
  • Knowledge of solving linear equations and constraints.
  • Ability to manipulate matrices and perform row operations.
NEXT STEPS
  • Study the concept of matrix rank and its implications for linear independence.
  • Learn about the construction of basis matrices in vector spaces.
  • Explore the properties of matrices with specific row and column constraints.
  • Investigate applications of zero row sum matrices in various mathematical contexts.
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Students of linear algebra, mathematicians, and educators looking to deepen their understanding of matrix spaces and their properties.

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Homework Statement



For my homework assignment, I'm supposed to find a basis for the space of 3x3 matrices that have zero row sums and separately for zero row columns. I am having a hard time with this as it seems to me that there are a lot of combinations I have to consider. For the first, it seems like the rows would have to consist of one 0, one 1, and one -1 in different orders... Is there a better way to do this other than brute force?

Homework Equations





The Attempt at a Solution

 
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Well, a general 3 by 3 matrix can be written
\begin{bmatrix}a & b & c \\ d & e & f \\ g & h & i\end{bmatrix}.
The condition that "row sums are 0" means that a+ b+ c= 0, d+ e+ f= 0, and g+ h+ i= 0. Solve that for, say, a, d, and e and replace them in the matrix. Since the space of all 3 by 3 matrices is 9 dimensional, and you have 3 "conditions", you will want 6 basis matrices.
 

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