Abstract. Since 2021, Russia has maintained a list of unfriendly countries. This and the import ban introduced in 2014 are some main economic sanctions uses to influence trading partners. paper attempts quantify effect putting partner on countries compared Russian ban. The study data trade flows between its partners from UN COMTRADE database for select agri-food products. Employing gravity fram...

Let G be a graph with n vertices. We denote the largest signless Laplacian eigenvalue of G by q1(G) and Laplacian eigenvalues of G by μ1(G) > · · · > μn−1(G) > μn(G) = 0. It is a conjecture on Laplacian spread of graphs that μ1(G)−μn−1(G) 6 n − 1 or equivalently μ1(G) + μ1(G) 6 2n − 1. We prove the conjecture for bipartite graphs. Also we show that for any bipartite graph G, μ1(G)μ1(G) 6 n(n − ...

It is easy to see that there is at most one pair of polynomials (q(x), r(x)) satisfying (1); for if (q1(x), r1(x)) and (q2(x), r2(x)) both satisfy the relation with respect to the same polynomial u(x) and v(x), then q1(x)v(x)+r1(x) = q2(x)v(x)+r2(x), so (q1(x)− q2(x))v(x) = r2(x)−r1(x). Now if q1(x)− q2(x) is nonzero, we have deg((q1 − q2) · v) = deg(q1 − q2)+deg(v) ≥ deg(v) > deg(r2 − r1), a c...

A hexachloro congener (Q1-hex) of the natural heptachloro-1'-methyl-1,2'-bipyrrole Q1 was recently observed as a byproduct of the Q1 synthesis. NMR investigation confirmed that Q1-hex has a proton on a carbon in beta-position to a nitrogen. Three isomers are possible that fulfill this prerequisite; unfortunately, however, the NMR data were not sufficient to distinguish among the three structura...

The terminology and notation used here are introduced in the following articles: [24], [27], [1], [3], [4], [2], [14], [12], [25], [22], [23], [11], [21], [8], [9], [6], [26], [15], [10], [18], [17], [5], [20], [19], [7], [13], and [16]. In this paper n is a natural number. We now state a number of propositions: (1) For all subsets A, B of E T such that A meets B holds proj1◦ A meets proj1◦ B. ...