_index.org

inclusion exclusion counting

Last edited: August 8, 2025

If an outcome can be from sets \(A=m\) or \(B=n\) with no overlaps, where \(A \cap B = \emptyset\), then, the total number of outcomes are \(|A| + |B| = m+n\)

If there are overlap:

\begin{equation} N = |A|+|B| - |A \cap B| \end{equation}

independently and identically distributed

Last edited: August 8, 2025

\(n\) random random variables are IID if they are

  1. independent
  2. identically distributed (see below)

“identically distributed”

Consider \(n\) random variables:

central limit theorem

when things are IID, you can use central limit theorem.

Index Index

Last edited: August 8, 2025

Here’s a list of all indexes:

This should be reflected on a fancier way on my home page.

inductor

Last edited: August 8, 2025

voltage across a inductor

\begin{equation} V = \epsilon = -L \dv{I}{t} \end{equation}

this is kind of a formulation of faraday’s law.

\begin{equation} I(t) = \frac{V_0}{R_1} (1-e^{\frac{-t}{\frac{L}{R}}}) \end{equation}

energy stored in an inductor

\begin{equation} E = \frac{1}{2} LI^{2} \end{equation}

inference

Last edited: August 8, 2025

inference is the act of updating the distribution of a random variable based on distribution of actually observed variables:

\begin{equation} P(X|Y) \end{equation}

where \(Y\) is observed, and we want to know how likely \(X\) would therefore be.

We call the set \(X\) the “query variables”, \(Y\) as “evidence varibales”, and anything that we didn’t use which connects the two variables as “hidden variables”.

If things are not in the right order of \(X\) and \(Y\), consider the Bayes rule.