Al-Kūhī's revision of Book I of Euclid's Elements

The 10th-century mathematician Abū Sahl al-Kūhī, one of the best geometers of medieval Islam, wrote several treatises on the first three books of Euclid's Elements. We present an edition and translation of al-Kūhī's revision of Book I of the Elements, in which he altered the book's focus to the theorems and rearranged the propositions. The most dramatic of the changes is the complete absence of all geometric constructions, suggesting that al-Kūhī preferred instead to use Euclid's Data, and the related procedures of analysis and synthesis, for constructions. Other novel aspects include a proof of Euclid's fourth postulate, the use of the parallel postulate early in the work, and a different proof of the Pythagorean theorem.

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Conformal biderivations of loop W (a,b) Lie conformal algebra

We study conformal biderivations of a Lie conformal algebra. First, we give the definition of a conformal biderivation. Next, we determine the conformal biderivations of loop W(a, b) Lie conformal algebra, loop Virasoro Lie conformal algebra, and Virasoro Lie conformal algebra. Especially, all conformal biderivations on Virasoro Lie conformal algebra are inner conformal biderivations.     

The universal modality, the center of a Heyting algebra, and the Blok–Esakia theorem

We introduce the bimodal logic , which is the extension of Bennett’s bimodal logic by Grzegorczyk’s axiom □(□(p→□p)→p)→p and show that the lattice of normal extensions of the intuitionistic modal logic WS5 is isomorphic to the lattice of normal extensions of , thus generalizing the Blok–Esakia theorem. We also introduce the intuitionistic modal logic WS5.C, which is the extension of WS5 by the axiom (p¬p)→(p→p), and the bimodal logic , which is the extension of Shehtman’s bimodal logic by Grzegorczyk’s axiom, and show that the lattice of normal extensions of WS5.C is isomorphic to the lattice of normal extensions of .     

Extension of Colombeau algebra to derivatives of arbitrary order , . Application to ODEs and PDEs with entire and fractional derivatives

We give an extension of Colombeau algebra of generalized functions to fractional derivatives. We apply it in solving ODEs and PDEs with entire and fractional derivatives with respect to temporal and spatial variables. We give applications to ODEs and PDEs driven by fractional derivatives of delta distribution.     

Monotonicity characteristic of Köthe-Bochner spaces

Estimates of the characteristic of monotonicity in Köthe-Bochner function spaces E(X) with some consequences are given. Characterizations of strict and uniform monotonicity of the sequence lattice are obtained.     

Representation type of the blocks of category in types and

In this paper a complete classification of the representation type of the infinitesimal blocks of the parabolic category for the complex simple Lie algebras of types F₄ and G₂ is given.     

Minimal rankings and the arank number of a path

Given a graph G, a function f:V(G)→{1,2,…,k} is a k-ranking of G if f(u)=f(v) implies every u-v path contains a vertex w such that f(w)>f(u). A k-ranking is minimal if the reduction of any label greater than 1 violates the described ranking property. The arank number of a graph, denoted ψ_r(G), is the largest k such that G has a minimal k-ranking. We present new results involving minimal k-rankings of paths. In particular, we determine ψ_r(P_n), a problem posed by Laskar and Pillone in 2000.