A positive integer n is called a Zumkeller number if the set of all the positive divisors of n can be partitioned into two disjoint subsets, each summing to σ(n)/2. In this paper, Generalizing further, near-Zumkeller numbers and k-near-Zumkeller numbers are defined and also some results concerning these numbers are established. Relations of these numbers with practical numbers are also studied in this paper.
This paper considers Linear two-parameter eigenvalue problems in terms of matrix operators. Generally, for spectral analysis two-parameter problem is reduced into a system of generalized eigenvalue problems using a special pair of determinant operator matrices on tensor product space. In this work, some inequalities on numerical range and numerical radius of this special pair of operator matrices arising from two-parameter problem will be derived.
Let G = (V,E) be a graph. An m-Zumkeller cordial labeling of the graph G is defined by an injective function f : V → N such that there exists an induced function f ∗ : E → {0, 1} defined by f ∗ (uv) = f (u) · f (v) that satisfies the following conditions- i. For every uv ∈ E, f ∗ (uv) = {█(1,if f (u) · f (v) is an m-Zumkeller number @ 0,otherwise )┤ ii. |ef ∗ (0) − ef∗ (1)| ≤ 1 where ef ∗ (0) and ef ∗ (1) denote the number of edges of the graph G having label 0 and 1 respectively under f ∗. In this paper we prove that there exist an m-Zumkeller cordial labeling of graphs in paths, cycles, comb graphs, ladder graphs, twig graphs, helm graphs, wheel graphs, crown graphs and star graphs.
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