Basic probability theory

수학노트
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introduction

  • Let \((\Omega, \mathcal{F}, P)\) be probability space
  • A real-valued function \(X : \Omega\to \mathbb{R}\) is called a random variable
  • let \(A\subseteq \mathbb{R}\) be the range of \(X\), \(A=\{s|X(s)=x,s\in S\}\). We call \(A\) the space of \(X\)
  • \(\{X=x\}\) denote the subset \(\{s|X(s)=x\}\) of \(\mathbb{R}\)
  • the induced probability measure \(P_X : \mathbb{R}\to [0,1]\)
  • probability density function \(f : \mathbb{R}\to [0,\infty)\) of \(X\) satisfies

\[ P_{X}(X\in A)=\int_A f(x)\, dx=1 \] and \[ P_{X}(X\in B)=\int_B f(x)\, dx \] for \(B\subseteq A\).