Beneficios de la notación de Peirce para los conectivos proposicionales binarios

Antecedentes: En la notación tradicional para los conectivos proposicionales binarios son tenidos en cuenta solamente algunos de estos. A lo largo del siglo XX fueron propuestas varias notaciones que subsanan esa falencia, dando lugar al planteamiento de interesantes problemas matemáticos. Objetivo: En este escrito se presenta la notación creada por el norteamericano Charles Peirce, se muestran algunas propiedades de las cuales goza esta simbología, y se evidencian sus ventajas con respecto a la tradicional. Método: Se describe la notación propuesta por Peirce, y se verifican algunas propiedades de carácter lógico geométrico y algebraico entre sus conectivos; también se analiza la posible actuación de estas propiedades en la notación usual. Resultados: Además de varias propiedades individuales y de múltiples relaciones entre los conectivos, las simetrías del sistema completo de los conectivos proposicionales binarios se evidencian de manera visual en los signos propuestos por Peirce. Conclusión: Diversas bondades de las cuales goza la notación propuesta por Peirce, permiten afirmar que la notación usual es superada de manera clara por la simbología diseñada por el científico norteamericano.Abstract Background: In traditional binary notation for propositional connectives only some of these ones are taken into account. Throughout the twentieth century several notations were proposed which overcome this flaw, leading to the proposal of interesting mathematical problems. Objective: This paper presents the notation created by the American Charles Peirce, showing some of the properties of this symbols, and evidencing the advantages of these compared to the traditional. Method: the notation proposed by Peirce is described, and some properties of the geometric and algebraic logical character among its connective are verified; also, the possible role of these properties in the traditional notation is analyzed. Results: In addition to several individual properties and multiple relations between the connectives, the symmetries of the full set of binary propositional connective is visually evident in the signs proposed by Peirce. Conclusion: Different benefits of the notation proposed by Peirce, support the conclusion that the usual notation is clearly surpassed by the symbolism designed by the American scientist.Palabras clave: Conectivo proposicional, Charles S. Peirce, operación, simetría, tabla de verdad.

Refining reduction in the lambda calculus

We introduce a λ-calculus notation which enables us to detect in a term, more β-redexes than in the usual notation. On this basis, we define an extended β-reduction which is yet a subrelation of conversion. The Church Rosser property holds for this extended reduction. Moreover, we show that we can transform generalised redexes into usual ones by a process called ‘term reshuffling’.

A note on locally soluble, normal closures of cyclic subgroups

This brief note has the threefold purpose of improving on an earlier theorem of the author [4], gathering together some results on normal closures (with rank restrictions) which are more or less implicit in the literature and providing a few examples which indicate the impossibility of improving these results in one way or another. The proofs are mostly routine and usually omitted. Most of the relevant background material can be found in [3], and references to these results will often indicate that minoradditional details (an easy induction, for example) are required. Throughout, 〈x〉G will denote the normal closure of the subgroup 〈x〉 of the group G. The usual notation is used for upper central and derived series.

Partitions of products

We will consider some partition properties of the following type: given a function F: ωω →2, is there a sequence H0, H1, … of subsets of ω such that F is constant on ΠiεωHi? The answer is obviously positive if we allow all the Hi's to have exactly one element, but the problem is nontrivial if we require the Hi's to have at least two elements. The axiom of choice contradicts the statement “for all F: ωω→ 2 there is a sequence H0, H1, H2,… of subsets of ω such that {i|(Hi) ≥ 2} is infinite and F is constant on ΠHi”, but the infinite exponent partition relation ω(ω)ω implies it; so, this statement is relatively consistent with an inaccessible cardinal. (See [1] where these partition properties were considered.)We will also consider partitions into any finite number of pieces, and we will prove some facts about partitions into ω-many pieces.Given a partition F: ωω → k, we say that H0, H1…, a sequence of subsets of ω, is homogeneous for F if F is constant on ΠHi. We say the sequence H0, H1,… is nonoverlapping if, for all i ∈ ω, ∪Hi > ∩Hi+1.The sequence 〈Hi: i ∈ ω〉 is of type 〈α0, α1,…〉 if, for every i ∈ ω, ∣Hi∣ = αi.We will adopt the usual notation for polarized partition relations due to Erdös, Hajnal, and Rado.means that for every partition F: κ1 × κ2 × … × κn→δ there is a sequence H0, H1,…, Hn such that Hi ⊂ κi and ∣Hi∣ = αi for every i, 1 ≤ i ≤ n, and F is constant on H1 × H2 × … × Hn.

On the stability of Kerr’s space-time

The stability of Kerr’s space-time with |a| < M , in the usual notation, against infinitesimal perturbations is discussed. No exponentially growing ‘normal modes’ occur. However, since (a) the exponentially decaying modes have not been shown to be complete, (b) there are normal modes with real frequencies, the stability of the Kerr space-time has not been established rigorously.

Double Meijer transformations of certain hypergeometric functions

Following the usual notation for generalized hypergeometric functions we let(a) denotes the sequence of A parametersthat is, there are A of the a parameters and B of the b parameters. Thus ((a))m has the interpretationwith a similar interpretation for ((b))m; Δ(k; α) stands for the set of k parametersand for the sake of brevity, the pair of parameters like α + β, α − β will be written as α ± β, the gamma product Γ(α + β) Γ(α − β) as Γ(α ± β), and so on.

The integration of generalized hypergeometric functions

In the usual notation for generalized hypergeometric functions we letwhereand (a) denotes the sequence of parametersThroughout the present paper we shall suppose that there are A of the a parameters, Bof the b parameters, and so on. Thus ((a))m is to be interpreted asand similar interpretations hold for ((b))m, etc.

Some expansions in products of hypergeometric functions

In the usual notation letwhere .Also, for the generalized hypergeometric function pFq(x) let us employ a contracted notation and writeThroughout the present paper i will run from 1 to p, I from 1 to P, and so on. Thus ((a) )m is to be interpreted as,and similar interpretations hold for ((A))m, etc.

Some expansions of generalized Whittaker functions

In the usual notation letwhere (a)n = a(a + 1)(a + 2)…(a + n − 1), (a)0 = 1.Dr L. J. Slater ((3), page 628) gave an expansion of the formfor all values of n and t, real or complex.

A Type of Alternant

We definewhere ap ≠ aq when p ≠ q. If N = Σλi, then the partition (λ1, λ2, …, λn) of N with λ1 ≥ λ2 ≥ … ≥ λn is denoted by (λ) and we setAll partitions will be in descending order and the usual notation for repeated parts will be used.