中国科学院数学与系统科学研究院期刊网

15 April 1954, Volume 4 Issue 2
    

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  • Acta Mathematica Sinica, Chinese Series. 1954, 4(2): 113-124. https://doi.org/10.12386/A1954sxxb0007
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    Let ω_1 and ω_2 be two complex numbers and τ=ω_2/ω_1. We suppose that the imaginary part of τ is positive. As usual, we use to denote Weierstrass' elliptic function. Let The purpose of the notes is to find the coefficients of the Fourier expansion of t(τ), namely We prove that where h h'≡-I (mod k),I_1 (z) is the Bessel function of the first order of pure imaginary argunment and λ (h,k) equals to 0, +1, -1 +i or -i according to the values of h and k belonging to various classes.
  • Acta Mathematica Sinica, Chinese Series. 1954, 4(2): 125-142. https://doi.org/10.12386/A1954sxxb0009
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    This paper describes the construction of a new function of n variables i,u,v,……,z,which becomes identical to the given function f(t,u,v,……, z) of n variables when (n-1) of the variables are each assigned their own specific values used in the construction of the function.In case of two variables, the surfaces of f(t, u) and coincide laong 4r sections at the values t_1,t_1′,t_2,t_2′,……,t_r, t_r′, u_1,u_1′,u_2,u_2′,……,u_r,u_r′. If both are ocntinuous and single-valued, actual examples indicate that the new function is a very close approximation of the original function f(t,u) within the region of cross-lines of coincidence.
  • Acta Mathematica Sinica, Chinese Series. 1954, 4(2): 143-170. https://doi.org/10.12386/A1954sxxb0010
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    Let (z)=(z~1,…, z~n) be n complex variables and be a domain of (z). Let H be an n-rowed Hermitian matrix of which the elements are analytic functions of z and z, where z denotes conjugate imaginary of z. We introduce fundamental Hermitian differential form dz H dz', where M' denotes the transposed and conjugate matrix of M. Let z = t (w) be a pseudo-conformal mapping, its Jacobian matrix being denoted by J(w)=J. It carries d z H dz' into dw K dw', where K=JHJ'.(1) Differentiating totally with respect to the variables z~1,…, z~n, we have dK=(JdH+dJH)J and dK·K~(-1) = J (dH·H~(-1))J~(-1)+ dJ·J~(-1).Consequently we have d(dK·K~(-1)) = J (d (dH·H~(-1)))J~(-1), i.e. d dk-dk·K~(-1)·dk′=J(d dH-dH·H~(-1)·dH′)J′,and then dw(d dK - dK·K~(-1)·dK') dw' = dz (d dH - dH·H~(-1)·dH')dz'. The Riemann curvature of the geometry so obtained is given by R=-dz(d dH-dH·H~(-1)·dH')dz'/(dz H dz')~2(*) Now we shall take a special form of H. Let φ_o (z), φ_1(z),…,φ_ν(z),… be a sequence (finite or infinite) of functions, analytic in without common zero and converges uniformly in any compact domain in We define We establish easily that H=K~(-2) NN', where N is an n×∞ matrix given by and Substituting H=1/K~2 NN' into (*),we have Since I-N'(NN')~(-1)N=(I-N'(NN')~(-1)N)(I-N'(NN')~(-1)N)'is positive definite,we deduce R≤2.The inequality is a best possible one,in fact,we found the extremal cases.Moreover the author proved also the following equality, which implies R≤2 immediately:It is not difficult to see that our result implies Fuchs' theorem on the theory of functions of several complex variables. It should be noticed that we assumed far less and our method is much simpler than that of Fuchs.We obtained also some results concerning the lower bound of the curvature. In fact, if the kernel is proportional to the volume density, the Riemann curvature≥-n.The method is not appropriate to be sketched in a short summery.
  • Acta Mathematica Sinica, Chinese Series. 1954, 4(2): 171-199. https://doi.org/10.12386/A1954sxxb0011
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    The present paper, as well as the preceding one with the same tide [6], contain the detailed proofs of results sketched in [1], §§5-6. It is proved that for a closed differentiable manifold, to any odd prime p, certain combinations by means of cup products of the classes, reduced mod p, with respect to any given differential structure of the manifold are in reality independent of that structure and therefore are topological in variants of the manifold. For p = 3, it turns out that the mod 3 classes are themselves topological invariants of the manifold. The proofs are based on the so-called "diagonal method", obtaining thus a connection between the classes and the Steenrod powers, of which the later one, in the case of a differentiable manifold, are of a character non-diffential, but purely topological.
  • Acta Mathematica Sinica, Chinese Series. 1954, 4(2): 201-221. https://doi.org/10.12386/A1954sxxb0012
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    In [1] the author introduced a method to construct a map [φ_1,φ_2, φ_3]:S~(r1+r2+r3-1)→X, if maps fi: S~(ri)→X(i=1, 2, 3) are given such that [f_i,f_i]~0 in X. Here he has extended this operation to construct an element, [φ_1,…,φ_n], of π_(r1+…+rn-1)(X) if elements a_i∈π_(ri) (X), (i=1,…,n) are given with appropriate properties. As a consequence a special cell complex, K_(r,n), is constructed which consists of one zero-dimensional cell, e~o, one n-dimensional cell, e~n, such that e~o ∪ e~n is an n-sphere, S~n, and one (kn)-dimensional cell if 1≤k≤r. Moreover, the (kn)-cell is attached by the map [φ_1,…,φ_k] which is so introduced that each a_i (i= 1,…, k) used in defining [φ_1,…, φ_k] is the class determined by the identity map of the sphere S~n (in K_(r,n)). The main theorem of this paper is π_(q+1) (S~(n+1))≈π_q(K_(r,n)), if n>1,q≤(r+1) n-2; π_(q+1)(S~2)≈π_q(K_(r,2)), if 11, for all q and particularly π_(q+1)(S~2)≈π_q(K_(∞,2)), q>1.Let E: π_q (S~n)→π_(q+1)(S~(n+1)) denote the suspension homomorphism. The author has successfully exhibited its kernel and its image. This implies many important results, e.g. (i) Pontrjagin theorem that π_5(S~3)≠0, (ii) simple proofs of the Frendenthal theorem that E is onto if q≦2n-1 and isomorphism onto if q≦2n-2, and (iii) extended G. W. Whitehead theorem about exact sequence regarding suspension, Hopf invariant and Whitehead product.
  • Acta Mathematica Sinica, Chinese Series. 1954, 4(2): 223-243. https://doi.org/10.12386/A1954sxxb0013
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    In this paper we shall study the problem of equivalence of the integral dx under the group of all contact transformations in the (x,y)-plane.Theorem 1. If the differential invariant and the differential invariant we can always choose n + 2 Pfaffian forms ω_o, ω_1,…, ω_(n+1) in an invariant way (i. e. independent of the choice of coordinate system) satisfying the following equations: where Ω_o is the sum of the exterior products in ω_1,…,ω_(n-1);Ω_i the sum of the exterior products in ω_1,…,ω_i(i=1,2,…, n);Ω_(n+1) the sum of the exterior products in ω_1,…,ω_(n+1).If I = 0, we can also choose n + 2 Pfaffian forms ω_o, ω_1,…,ω_(n+1) in an invariant way satistying the similar equations.If the differential invariant R_(11n+1)= 0, in which case the function F(x,y,y',…, y~((n))) is reduced to the form F = (A y~((n)) + B)~((1/n)), n>3, by a contact transformation of the plane, where A and B are the functions of x, y, y', …, y~((n-1)) only. We proved thatTheorem 2. If R_(11n+1) = 0, we can still choose n+2 Pfaffian forms (?)_o,(?)_1,…, (?)_(n+1) in an invariant way satisfying the following equations:where Ω_o is the quadratic exterior form in (?)_1,…,(?)_(n-1);Ω_(i-1) the quadratic exterior form in (?)_1,…, (?)_(i-2) (i = 2,…, n); Ω_n, Ω_(n+1) the quadratic exterior forms in (?)_1,…,(?)_(n-1).
  • Acta Mathematica Sinica, Chinese Series. 1954, 4(2): 245-257. https://doi.org/10.12386/A1954sxxb0014
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    Suppose f(z) is regular in |z|<1 and denote by W the Riemann domain which is the transform of |z|<1 by f. Let w(R)be the area (regions covered multiply being counted multiply) of that portion of W which lies in the circle |ω|≤R;then if W(R) ≤ p π R~2 for all R > 0, where p is a positive number (not necessarily integral), we shall say that f(z) is a mean p-valent. The totality of all such functions form a classwhich shall be denoted by S_p. In particular, we denote S_1 by S.This class of functions was defined by J. E. Littlewood, and have been studied by D. C. Spencer and Alenytsun.The aim of the present note is to establish some new results for S_p.Theorem 1. If and then where.Equality holds only if f(z)= az~p, where a is a constant.Theorem 1 is an extension of Biernacki's theorem.Theorem 2. If then where.Theorem 3. Let If holds for |z|<1 with constants M and α,α>1/2,then where M_o depends only upon M, p, α.Theorem 2 and Theorem 3 are extended form of Golusin's results in the theory of schlicht functions.Theorem 4. If f(z)= z +…∈S, then f(z) is schlicht in the circle |z|
  • Acta Mathematica Sinica, Chinese Series. 1954, 4(2): 259-262. https://doi.org/10.12386/A1954sxxb0015
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    Let be regular and schlicht in the domain 1<|ζ|<∞. Golusin and Shah proved that where γ, ζ are any complex numbers with |ζ|>1.If thenThe object of the present note is to improve .(1), (2), (3) and (4) into following forms:Theorem. Let be regular and schlicht in 1<|ζ|<∞.Then,if where γ, ζ are any complex numbers with |ζ|>1 and m≥n.