Zermelo's discovery of the “Russell Paradox”

In his 1908 paper on the Well-Ordering Theorem, Zermelo claimed to have found “Russell's Paradox” independently of Russell. Here we present a short note, written by E. Husserl in 1902, which contains a detailed exposition of Zermelo's original version of the paradox. We add some comments concerning the date of Zermelo's discovery, the circumstances which caused Husserl to write down Zermelo's argument, and the argument itself.     

The invariance of dimension: Problems in the early development of set theory and topology [1]

In 1878 Georg Cantor proved that unique, one-to-one mappings could be constructed between spaces of arbitrary yet different dimension. This paper is devoted to a detailed analysis of the earliest attempts to deal with the implications of that proof. Dedekind was the first to suggest that continuity was a key to the problem of dimensional invariance. Lüroth, Thomae, Jürgens and Netto offered solutions, Netto's being the most interesting in terms of the specifically topological character of his paper. Cantor finally offered a faulty proof in 1879 that domains of different dimension could not be mapped continuously onto each other by means of a one-to-one correspondence. Finally, consideration is given to the reasons why Netto's and Cantor's faulty proofs went unchallenged for twenty years, until Jürgens criticized them both in 1899.     

Arrow's theorem is not a surprising result

Arrow's theorem asserts that it is impossible to find a procedure which aggregates n given complete preorders into one complete preorder and which has ‘rational’ properties.Some authors have proposed to solve this problem in building what could be called ‘preaggregation methods’. The purpose of this paper is to study the Arrow's problematic in this context.The obtained results lead to an interpretation of Arrow's theorem which shows that it is rather natural, although many authors present it as a surprising result or even as a paradox.The last section compares the structures of the sets of decisive sets associated to aggregation and preaggregation procedures.     

错用罗素悖论-康托在集合论中的两个逻辑性错误

分析了罗素悖论与康托的实数集合不可数证明及康托定理S〈P（S）证明之间的本质性联系，发现康托的这两个非构造性证明与罗素悖论有完全相同的思路，但是康托犯了两个逻辑性错误而使他误用了这个悖论思路。得到明确的结论：康托在集合论中如上两个证明里的核心部分实际上是罗素悖论的翻版，这两个证明中的思路与做法是错误的，这样的证明结果没有科学性。     

Some Paradoxes in Special Relativity and the Resolutions

The special theory of relativity is the foundation of modern physics, but its unusual postulate of invariant vacuum speed of light results in a number of plausible paradoxes. This situation leads to radical criticisms and suspicions against the theory of relativity. In this paper, from the perspective that the relativity is nothing but a geometry, we give a uniform resolution to some famous and typical paradoxes such as the ladder paradox, the Ehrenfest’s rotational disc paradox. The discussion shows that all the paradoxes are caused by misinterpretation of concepts. We misused the global simultaneity and the principle of relativity. As a geometry of Minkowski space-time, special relativity can never result in a logical contradiction.     

Peirce's place in mathematics

This article compares treatments of the infinite, of continuity and definitions of real numbers produced by the German mathematician Georg Cantor and Richard Dedekind in the late 19th century with similar interests developed at virtually the same time by the American mathematician/philosopher C. S. Peirce. Peirce was led, not by the internal concerns of mathematics which had motivated Cantor and Dedekind, but by research he undertook in logic, to investigate orders of infinite sets (multitudes, in his terminology), and to introduce the related concept of infinitesimals. His arguments in support of the mathematical and logical validity of infinitesimals (which were rejected by such eminent mathematicians as Cantor, Peano, and Russell at the turn of the century) are considered. Attention is also given to the connections between Peirce's mathematics, his philosophy, and especially his interest in continuity as it was related to his Pragmatism.     

Paradoxes as a window to infinity

This study examines approaches to infinity of two groups of university students with different mathematical background: undergraduate students in Liberal Arts Programmes and graduate students in a Mathematics Education Master's Programme. Our data are drawn from students’ engagement with two well-known paradoxes – Hilbert's Grand Hotel and the Ping-Pong Ball Conundrum – before, during, and after instruction. While graduate students found the resolution of Hilbert's Grand Hotel paradox unproblematic, responses of students in both groups to the Ping-Pong Ball Conundrum were surprisingly similar. Consistent with prior research, the work of participants in our study revealed that they perceive infinity as an ongoing process, rather than a completed one, and fail to notice conflicting ideas. Our contribution is in describing specific challenging features of these paradoxes that might influence students’ understanding of infinity, as well as the persuasive factors in students’ reasoning, that have not been unveiled by other means.     

Discussions on Newton's infinitesimals in eighteenth-century Anglo-America

The controversy in England over Newton's fluxionary calculus following the publication in 1734 of Bishop George Berkeley's The Analyst was reflected in the correspondence between Cadwallader Colden of New York and his friends in the middle 1740s. Colden wrote “An Introduction to the Doctrine of Fluxions” after reading The Analyst, and it was the occasion for the discussions that followed. His friends either doubted the value of the calculus and the validity of infinitesimals, or were noncommittal. Colden's essay was the only published defense of Newton's calculus by a colonist in eighteenth-century Anglo-America. There was a lack of interest in the calculus in both Great Britain and America until well into the nineteenth century. In the following we suggest reasons for that lack of interest.     

Maharam's problem

We solve Maharam's problem [D. Maharam, An algebraic characterization of measure algebras, Ann. Math. 48 (1947) 154–167. [3]], also known as the Control Measure Problem. We construct a non-zero exhaustive submeasure on the algebra of clopen sets of the Cantor set that is not absolutely continuous with respect to a measure. To cite this article: M. Talagrand, C. R. Acad. Sci. Paris, Ser. I 342 (2006).     

Equity,efficiency and rights in social choice

The impossibility of a Paretian liberal presented by Sen shows the incompatibility of the Pareto principle with a mild claim of libertarian rights when they are required of the collective choice rule with unrestricted domain. In view of the profound implications of this paradox, it is no wonder that there are many serious attempts in the literature to seek for a general resolution thereof. In this paper, we try to explore an avenue which has been left relatively less cultivated in the attempts to try to find a way out of this paradox, the essential idea thereof being to restrict the ‘legitimate’ exercise of the liberatarian rights by the claims of justice or equity. It will be shown that the gist of the successful resolution of the Pareto libertarian paradox along this line lies in the impartiality of the principle of justice held by the individuals and the prevalence of the sympathetic acceptance of each other's subjective preferences.     

Chapter 1. Extension of the fundamental theorem of finite semigroups

This paper proves that some useful commutivity relations exist among semigroup wreath product factors that are either groups or combinatorial “units” U₁, U₂, or U₃. Using these results it then obtains some characterizations of each of the classes of semigroups buildable from U₁'s, U₂'s, and groups (“buildable” meaning “dividing a wreath product of”).We show that up to division U₁'s can be moved to the right and U₂'s, and groups to the left over other units and groups, if it is allowed that the factors involved be replaced by their direct products, or in the case of U₂, even by a wreath product. From this it is deduced that U₁'s and U₂'s do not affect group complexity, that any semigroup buildable from U₁'s, U₂'s, and groups has group complexity 0 or 1, and that all such semigroups can be represented, up to division, in a canonical form—namely, as a wreath product with all U₁'s on the right, all U₂'s on the left, and a group in the middle. This last fact is handy for developing charactérizations.An embedding theorem for semigroups with a unique 0-minimal ideal is introduced, and from this and the commutivity results and some constructions proved for RLM semigroups, there is obtained an algebraic characterization for each class of semigroups that is a wreath product-division closure of some combination of U₁'s, U₂'s, and the groups. In addition it is shown, for i = 1,2,3, that if the unit U_i does not divide a semigroup S, then S can be built using only groups and units not containing U_i. Thus, it can be deduced that any semigroup which does not contain U₃ must have group complexity either 0 or 1. This then establishes that indeed U₃ is the determinant of group complexity, since it is already proved that both U₁ and U₂ are transparent with regard to the group complexity function, and it is known that with U₃ (and groups) one can build semigroups with complexities arbitrarily large. Another conclusion is a combinatorial counterpart for the Krohn-Rhodes prime decomposition theorem, saying that any semigroups can be built from the set of units which divide it together with the set of those semigroups not having unit divisors. Further, one can now characterize those semigroups which commute over groups, showing a semigroup commutes to the left over groups iff it is “R₁” (i.e., does not contain U₁, i.e., is buildable form U₂'s and groups), and commutes to the right over groups iff it does not contain U₂ (i.e., is buildable from groups and U₁'s). Finally, from the characterizations and their proofs one sees some ways in which groups can do the work of combinatorials in building combinatorial semigroups.     

A stochastic calculus for continuous N-parameter strong martingales

Let M be a 4N-integrable, real-valued continuous N-parameter strong martingale. Burkholder's inequalities prove to be an adequate tool to control the quadratic oscillations of M and the integral processes associated with it (i.e. multiple 1-stochastic integrals with respect to M and its quadratic variation) such that a 1-stochastic calculus for M can be designed. As the main results of this calculus, several Ito-type formulas are established: one in terms of the integral processes associated with M, another one in terms of the so-called ‘variations’, i.e. stochastic measures which arise as the limits of straightforward and simple approximations by Taylor's formula; finally, a third one which is derived from the first by iterated application of a stochastic version of Green's formula and which may be the strong martingale form of a prototype for general martingales.     

Tax evasion and the prisoner's dilemma

This analysis expands the model of tax evasion suggested by Allingham and Sandmo (1972) to include public goods, financed by revenues from taxation and penalties. We argue that this leads to a Pareto inferior equilibrium outcome of individual declarations both in models of competitive and interdependent behaviour, thus linking the paradox to the Prisoner's Dilemma, well known from game theory. It is further claimed that a government led by utilitarian welfare standards will perpetuate tax evasion in the case of positive variable costs of detection.     

Solution of equations in Boolean algebra

The explicit form of solutions of Boolean equations with one unknown is obtained. The effectiveness of the method is demonstrated for a number of equations whose solution previously has been found only in “tabular” form. The proposed approach leads to a method for solving systems of equations in Boolean set algebra. We use it to analyze the famous paradoxes of set theory, such as the barber paradox and the liar paradox, as well as Russell's and Cantor's paradoxes. Translated from Nelineinaya Dinamika i Upravlenie, pp. 119–132, 1999.     

Gray codes in graphs of subsets

Let G(n,k) be a graph whose vertices are the k-element subsets of an n-set represented as n-tuples of “O's” and “1's” with k “1's”. Two such subsets are adjacent if one can be obtained from the other by switching a “O” and a “1” which are in adjacent positions, where the first and nth positions are also considered adjacent. The problem of finding hamiltonian cycles in G(n,k) is discussed. This may be considered a problem of finding “Gray codes” of the k-element subsets of an n-set. It is shown that no such cycle exists if n and k are both even or if k=2 and n?7 and that such a cycle does exist in all other cases where k?5.     

Gregory's converging double sequence: A new look at the controversy between huygens and gregory over the “analytical” quadrature of the circle

As is well known, upon publication of his Vera circuli et hyperbolae quadratura (Padua 1667), James Gregory became involved in a bitter controversy with Christiaan Huygens over the truth of one of his major propositions. It stated that the area of a sector of a central conic cannot be expressed “analytically” in terms of the areas of an inscribed triangle and a circumscribed quadrilateral. Huygens objected to Gregory's method of proof, and expressed doubts as to its validity. As Gregory's iterative limiting process, employing an infinite double sequence, uses a combination of geometric and harmonic means, one may apply to it methods developed by the young Gauss for dealing with a similar process based on the combination of arithmetic and geometric means. This yields both the Leibnizian series forπ/4 and the product found by Vie`te for2/π, and thus serves to illuminate the structure of Gregory's procedure and the nature of Huygens' criticism.     

The formulation of dynamical contact problems with friction in the case of systems of rigid bodies and general discrete mechanical systems—Painlevé and Kane paradoxes revisited

The dynamics of mechanical systems with a finite number of degrees of freedom (discrete mechanical systems) is governed by the Lagrange equation which is a second-order differential equation on a Riemannian manifold (the configuration manifold). The handling of perfect (frictionless) unilateral constraints in this framework (that of Lagrange’s analytical dynamics) was undertaken by Schatzman and Moreau at the beginning of the 1980s. A mathematically sound and consistent evolution problem was obtained, paving the road for many subsequent theoretical investigations. In this general evolution problem, the only reaction force which is involved is a generalized reaction force, consistently with the virtual power philosophy of Lagrange. Surprisingly, such a general formulation was never derived in the case of frictional unilateral multibody dynamics. Instead, the paradigm of the Coulomb law applying to reaction forces in the real world is generally invoked. So far, this paradigm has only enabled to obtain a consistent evolution problem in only some very few specific examples and to suggest numerical algorithms to produce computational examples (numerical modeling). In particular, it is not clear what is the evolution problem underlying the computational examples. Moreover, some of the few specific cases in which this paradigm enables to write down a precise evolution problem are known to show paradoxes: the Painlevé paradox (indeterminacy) and the Kane paradox (increase in kinetic energy due to friction). In this paper, we follow Lagrange’s philosophy and formulate the frictional unilateral multibody dynamics in terms of the generalized reaction force and not in terms of the real-world reaction force. A general evolution problem that governs the dynamics is obtained for the first time. We prove that all the solutions are dissipative; that is, this new formulation is free of Kane paradox. We also prove that some indeterminacy of the Painlevé paradox is fixed in this formulation.