Definition Given n实例 instance,x∈X, where X is the instance language or instance space Issue: how to represent text documents 固定的类别集合 categories: C={c1,C2…,Cn} a Determine. The category of X:c(ⅩX)∈C, Where o(x) is a categorization function分类函数 We want to know how to build categorization functions( classifiers分类器”)Definition ◼ Given: ◼ 实例 instance, xX, where X is the instance language or instance space. ◼ Issue: how to represent text documents. ◼ 固定的类别集合 categories: ◼ C = {c1 , c2 ,…, cn} ◼ Determine: ◼ The category of x : c(x)C, where c(x) is a categorization function 分类函数 ◼ We want to know how to build categorization functions (“classifiers 分类器” )