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Notation

Defined as

\(\triangleq\) means “is defined as”. For example, read:

\[i \triangleq \sqrt{-1}\]

as “\(i\) is defined as the square root of -1.”

Implies

Read \(a \implies b\) as “\(a\) implies \(b\)“.

Biconditional

See: wikipedia on biconditional.

Read \(a \iff b\) as “\(a\) if and only if \(b\)“.

Set membership

\(\in\) means “in” or “one of”. For example:

\[k \in 0, 2, 4\]

means that the value \(k\) can take any of the three values 0, 2 or 4.

\(\notin\) means “not in” or “not one of”. For example:

\[k \notin 1, 3, 5\]

means that the value \(k\) can not take any of the three values 1, 3 or 5, but, all other things being equal, can take any other value.

Vectors

Read \(\vec{v}\) as “vector v”.

See Vectors and dot products.

End of proof

Read \(\blacksquare\) as “This completes the proof”.