= Solution
The <gamma matrices> represent the spacetime <Clifford algebra>. With the <Minkowski metric> convention above,
$$
\boxed{\{\gamma^\mu,\gamma^\nu\}=\gamma^\mu\gamma^\nu+\gamma^\nu\gamma^\mu=2\eta^{\mu\nu}I_4.}
$$
The braces denote the <anticommutator>. Consequently $(\gamma^0)^2=I_4$, $(\gamma^i)^2=-I_4$, and distinct <gamma matrices> anticommute. The <identity matrix> is essential: the right side is a matrix equality, not a <scalar> equality. These signs agree with the explicit <Dirac representation of the gamma matrices> in the next part.
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