Vol. 14, No. 3 2007 218–225 “ ” ∗ Invitation of All People to Statistical Physics Sumio Watanabe Tokyo Institute of Technology∗ 1. ∗∗ ∗ 226-8503 4259 ∗∗ 2. 0 219 2.1 R n Rn Rn = {(x1, x2, ..., xn) ; |xi| < ∞ (∀i)} n x = (x1, x2, ..., xn) �x� = � x2 1 + x2 2 + · · · + x2 n n En En = {x ∈ Rn ; �x� < ∞} n Rn = En . 2.2 n ∞ R∞ = {(x1, x2, ..., xn, ...) ; |xi| < ∞(∀i)} x = (x1, x2, ..., xn, ...) �x� =