First Principles AI

Accedmychevron_right11thchevron_rightmathchevron_rightMatrices And Determinantschevron_rightExercise 4.1

Key idea

For an $n\times n$ identity matrix $I_n$ :

I_nA=A,\qquad AI_n=A

This follows from the Kronecker delta identity:

\delta_{ik}=\begin{cases}1,& i=k\\0,& i\ne k\end{cases}