The complete elliptic integrals K and E are functions of their modulus k which satisfy the equations

respectively.

We show that the involution $\theta(a\otimes b)=a^*\otimes b^*$ on the Haagerup tensor product $A\otimes_{\mrm{H}}B$ of $C^*$-algebras $A$ and $B$ is an isometry if and only if $A$ and $B$ are commutative. The involutive Banach algebra $A\otimes_{\mrm{H}}A$ arising from the involution $a\otimes b\to b^*\otimes a^*$ is also studied.

AMS 2000 Mathematics subject classification: Primary 46L05; 46M05

Nearfields and near-rings are related to many other structures and needed for several representation theorems. Therefore it is important to gain knowledge about the structure of near-rings and nearfields and to find construction methods. The first examples of proper nearfields were constructed by L.E. Dickson 1905, they were finite. 30 years later H. Zassenhaus completely determined the finite nearfields his attention having been attracted to them by the study of certain permutation groups. By the axiomatization of Dickson's methods, H. Karzel succeeded in giving new examples of infinite nearfields. In the extensive generalization by J. Timm the so-called “Dicksonian processes” are the most important tool for constructions of nearfields and near-rings. The report (44) by H. Wähling is a summary of the results on nearfields obtained so far.

The methods now adopted in the teaching of elementary geometry have made it most important that the teacher should have clear views upon the nature of the problems which are soluble by Euclid's methods: that is, with the aid of the ruler and compass only. With this general question I have dealt in another place. In this paper I give a short account of the argument by means of which Gauss proved that the only regular polygons of n sides, which can be constructed by Euclid's methods, are those in which n, when broken up into prime factors, takes the form

m1, m2, m3,…mr being all different.

We will present an investigation of (ε, δ)-Freudenthal–Kantor supertriple systems that are intimately related to Lie supertriple systems and Lie superalgebras. We can also introduce a super analogue of Nijenhuis tensor and almost-complex structure in differential geometry.

It is a well-known fact and easy to prove that if Γ and Γ′ be any two class-cubics and P a variable point, such that the pencil of lines from P to Γ apolarly separate the pencil of lines from P to Γ′, then the locus of P is a cubic curve G called the “apolar locus” of Γ and Γ′. Also, Γ and Γ′ are said to be co-apolar class-cubics” of G, or simply “co-apolars” of G. The problem of finding the general system of co-apolars of a given cubic curve has not yet been completely solved, but particular and more important cases have been investigated by me in several papers contributed to the London Mathematical Society. In the present communication I propose to deal with the most general solution of the above problem.

It is very seldom that any properties of a pencil of cubics can be discovered beyond some very general ones. The above case yields, however, some interesting results. It presented itself to me when I was considering the apolar generation of cubic curves which was published in the Proceedings of the London Mathematical Society (Ser. 2, Vol. 9, Part 3), and which I shall have frequent occasion to refer to in the present paper.

We consider certain exponential box splines E on a three-direction mesh whose exponents satisfy a symmetry condition. It is shown, in particular, that given bounded data on the integer lattice in R2, there is a unique bounded combination of integer translates of E that interpolates the data. When all exponents are zero, this reduces to a result of de Boor, Höllig and Riemenschneider in [2]. Unlike the proof in [2] we use only elementary analysis and do not employ any computer calculations.

Let S be a regular semigroup. An inverse subsemigroup S° of S is an inverse transversal if |V(x)∩S°| = 1 for each x∈S, where V(x) denotes the set of inverses of x. In this case, the unique element of V(x)∩S° is denoted by x°, and x°° denotes (x°)–1. Throughout this paper S denotes a regular semigroup with an inverse transversal S°, and E(S°) = E° denotes the semilattice of idempotents of S°. The sets {e∈S:ee° = e} and {f∈S:f°f=f} are denoted by Is and Λs, respectively, or simply I and Λ. Though each element of these sets is idempotent, they are not necessarily sub-bands of S. When both I and Λ are sub-bands of S, S° is called an S-inverse transversal. An inverse transversal S° is multiplicative if x°xyy°∈E°, and S° is weakly multiplicative if (x°xyy°)°∈E° for every x, y∈S. A band B is left [resp. right] regular if e f e = e f [resp. e f e = f e], and B is left [resp. right] normal if e f g = e g f [resp. e f g = f e g] for every e, f, g∈B. A subset Q of S is a quasi-ideal of S if QSQ ⊆ S.

A scalar multiple of the Kähler form of a Kähler manifold is called a Kähler magnetic field. We are focused on trajectories of charged particles under this action. As a variation of trajectories we define a magnetic Jacobi field. In this paper we discuss a comparison theorem on magnetic Jacobi fields, which corresponds to the Rauch's comparison theorem.

In [6] the structure of any real valued length function on an abelian group G is determined. It is shown there, in Theorem 6.1., that such a length function is an extension of a non-Archimedean length function l1 on N by an Archimedean length function l2 on H=G/N. Any non-Archimedean length function is given by a chain of subgroups, as described in [5], and following from results of Nancy Harrison [2], the length l2 is essentially the absolute value function on a subgroup of R. In the situation above if N≠G then N is a subgroup of G whose elements have bounded lengths. In this paper we show that it is an easy consequence of techniques developed in [1] that this result can be extended to hypercentral groups, thus determining the structure of any length function in this case. We point out that the result does not extend to soluble groups. The infinite dihedral group D∞ is soluble. However if D∞ is regarded as a free product of two cyclic groups of order 2 and is given the length function associated with a free product, as described by Lyndon [3], then N is not a subgroup of D∞, and the lengths of its elements are unbounded.

For each finite group G, let G denote the set of all normal subgroups of the modular group Γ = PSL2(ℤ) with quotient group isomorphic to G; since Γ is finitely generated, the number NG = |G| of such subgroups is finite. We shall be mainly concerned with the case where G is the linear fractional group PSL2(q) over the Galois field GF(q), in which case we shall write (q) and N(q) for G and NG; for q>3, PSL2(q) is simple, so the elements of (q) will be maximal normal subgroups of Γ.

The point known in elementary geometry by the name of Tarry was first discussed by that writer as the point of concurrence of the perpendiculars respectively from the vertices of the base-triangle to the corresponding sides of Brocards first triangle. Tarry's point is the point of the circumcircle diametrically opposite to Steiner's point, which is the fourth common point of the circumcircle and Steiner's circumellipse

Definition.—If tivo angles hare the same vertex and the same bisector, the sides of either angle are isogonal to each other with respect to the other angle.

Thus the isogonal of AP with respect to ∠ BAC is the image of AP in the bisector of ∠ BAC. It is indifferent whether the bisector of the interior ∠ BAC be taken, or the bisector of the angle adjacent to it; the isogonal of AP remains the same.

Necessary and sufficient conditions are found on an ideal a⊲ℤ[x] for the additive group [a]+ of ℤ[x]/a to be finite and cyclic. As a consequence, the abelianizations of certain cyclically-presented groups are computed explicitly.

This paper deals with the multivariate normal distribution in the symmetrical case when the frequency function may be reduced to

This is the usual distribution occurring for a series of similar independent observations or for the firing of shots at a target.