下記は、偏微分方程式の基本解とか書いてあった記憶あり (参考) https://en.wikipedia.org/wiki/Malgrange%E2%80%93Ehrenpreis_theorem Malgrange–Ehrenpreis theorem In mathematics, the Malgrange–Ehrenpreis theorem states that every non-zero linear differential operator with constant coefficients has a Green's function. It was first proved independently by Leon Ehrenpreis (1954, 1955) and Bernard Malgrange (1955–1956).
This means that the differential equation 略 where P is a polynomial in several variables and δ is the Dirac delta function, has a distributional solution u.
Proofs The original proofs of Malgrange and Ehrenpreis were non-constructive as they used the Hahn–Banach theorem. Since then several constructive proofs have been found. There is a very short proof using the Fourier transform and the Bernstein–Sato polynomial, as follows. By taking Fourier transforms the Malgrange–Ehrenpreis theorem is equivalent to the fact that every non-zero polynomial P has a distributional inverse. 0003132人目の素数さん2024/01/13(土) 11:17:47.21ID:bMiYMtT5>>1 885 名前:132人目の素数さん[sage] 投稿日:2023/12/31(日) 15:50:49.09 ID:xhhv+g7J [1/2] m/n=log(π) m、nは互いに素な正の整数 ↔ e^{m/n}=π ↔ e^m=π^n e<π<e^2 から e<n<2e ∴∃i=1,…,m-1 m=n+i ∴e^i=(π/e)^n<(1+(π-e)/e)^n <(1+(3.2-2.7)/(2.7))^n=(1+(32-27)/(27))^n=(1+1/(27/5))^n <(1+1/5)^n <(1+1/π)^π <lim_{x→+∞}(1+1/x)^x=e ∴矛盾 ∴log(π) は無理数
(参考) https://en.wikipedia.org/wiki/Bernstein%E2%80%93Sato_polynomial Bernstein–Sato polynomial In mathematics, the Bernstein–Sato polynomial is a polynomial related to differential operators, introduced independently by Joseph Bernstein (1971) and Mikio Sato and Takuro Shintani (1972, 1974), Sato (1990). It is also known as the b-function, the b-polynomial, and the Bernstein polynomial, though it is not related to the Bernstein polynomials used in approximation theory. It has applications to singularity theory, monodromy theory, and quantum field theory.
Severino Coutinho (1995) gives an elementary introduction, while Armand Borel (1987) and Masaki Kashiwara (2003) give more advanced accounts.
Definition and properties Definition and properties If f(x) is a polynomial in several variables, then there is a non-zero polynomial b(s) and a differential operator P(s) with polynomial coefficients such that 略 The Bernstein–Sato polynomial is the monic polynomial of smallest degree amongst such polynomials b(s). Its existence can be shown using the notion of holonomic D-modules.
Kashiwara (1976) proved that all roots of the Bernstein–Sato polynomial are negative rational numbers.
Nero Budur, Mircea Mustață, and Morihiko Saito (2006) generalized the Bernstein–Sato polynomial to arbitrary varieties.
Note, that the Bernstein–Sato polynomial can be computed algorithmically. However, such computations are hard in general. There are implementations of related algorithms in computer algebra systems RISA/Asir, Macaulay2, and SINGULAR.
Applications ・The Malgrange–Ehrenpreis theorem states that every differential operator with constant coefficients has a Green's function. By taking Fourier transforms this follows from the fact that every polynomial has a distributional inverse, which is proved in t 0006132人目の素数さん2024/01/13(土) 11:57:19.56ID:mq8hyzN8 スレタイに数学が入っていれば何もかも許されます。 0007132人目の素数さん2024/02/14(水) 22:15:36.13ID:BMdi34BM 梅の季節 0008132人目の素数さん2024/02/22(木) 07:55:13.09ID:liMOzQ9j 今日は寒さにご注意 0009132人目の素数さん2024/02/23(金) 09:12:10.37ID:t0Au/Qsl 今日も寒い 10度未満 0010132人目の素数さん2024/02/23(金) 12:20:07.90ID:JmJdUVdi 寒すぎるッピ! 賢ジャァ!!どうにかしろ! 0011132人目の素数さん2024/02/24(土) 07:11:08.19ID:S66BSOV1 5度 0012132人目の素数さん2024/02/28(水) 22:29:01.99ID:frCURa+q そろそろ春一番 0013132人目の素数さん2024/02/28(水) 23:41:48.02ID:2EcY62OY>>12 2月15日にすんだ 0014132人目の素数さん2024/02/29(木) 07:18:51.69ID:xz0hzExI 2024年は北陸、関東、四国では2月15日に春一番が吹いたと気象庁から発表があったぞ! 0015132人目の素数さん2024/02/29(木) 15:45:03.05ID:hGxmq4XH 🥥🌺https://youtu.be/6yb_4evq2Ng?si=itXbyn_xKG3YNDwf🍹;🏝🐚 0016132人目の素数さん2024/02/29(木) 15:51:44.32ID:hGxmq4XH そぅだょ 当たり前だょなぁ? ァ腐タアァッ-!ゥ"ァㇾンタ淫なんだぞ! もぅとっくに🥥🌈こ↑こ↓なつ🌺🌅だょなぁ… こ↑こ↓なつ💓i💔land🏝なんだょなぁ…