∫[X]j(x)m(dx)=Σ[i=1;n]αim(Ai)
f-(x)=Max(-f(x),0)
f-1 (Ａ∩Ｂ) ＝f-1 (Ａ) ∩f-1
df/dx=lim[⊿x→0]{f(x+⊿)-f(x)}/
lim[x→0](1-cos(x))/x=0
K={(x,y)}|0≦x≦1,0≦y≦x}