The El Niño/Southern Oscillation (ENSO) phenomenon is the dominant climatic fluctuation on interannual time scales. It is an irregular oscillation with a distinctive broadband spectrum. In this article, we discuss recent theories that seek to explain this irregularity. Particular attention is paid to explanations that involve the stochastic forcing of the slow ocean modes by fast atmospheric tr...

Let Γ=(VΓ,EΓ) be a simple undirected graph with finite vertex set VΓ and edge EΓ. A total n-labeling α:VΓ∪EΓ→{1,2,…,n} is called irregular labeling on Γ if for any two different edges xy x′y′ in EΓ the numbers α(x)+α(xy)+α(y) α(x′)+α(x′y′)+α(y′) are distinct. The smallest positive integer n such that can labeled by irregularity strength of Γ. In this paper, we provide some asymmetric graphs sym...

We investigate a modification of well known irregularity strength of graph, namely the total edge irregularity strength. An edge irregular total k-labeling φ : V ∪E → {1, 2, . . . , k} of a graph G is a labeling of vertices and edges of G in such a way that for any two different edges uv and u′v′ their weights φ(u)+φ(uv)+φ(v) and φ(u′)+φ(u′v′)+φ(v′) are distinct. The total edge irregularity str...

Let ( , ) G V E be a simple graph. For a total labeling { } : 1,2,3,..., V E k ∂ ∪ → the weight of a vertex x is defined as ( ) ( ) ( ). xy E wt x x xy ∈ = ∂ + ∂ ∑ ∂ is called a vertex irregular total k-labeling if for every pair of distinct vertices x and y, ( ) ( ). wt x wt y ≠ . The minimum k for which the graph G has a vertex irregular total k-labeling is called the total vertex irregularit...

As a standard notation, assume that G = G(V,E) is a finite, simple and undirected graph with p vertices and q edges. A labeling of a graph is any mapping that sends some set of graph elements to a set of numbers (usually positive integers). If the domain is the vertex-set or the edge-set, the labelings are called respectively vertex-labelings or edge-labelings. If the domain is V ∪E then we cal...

A total vertex irregular k-labeling φ of a graph G is a labeling of the vertices and edges of G with labels from the set {1, 2, . . . , k} in such a way that for any two different vertices x and y their weights wt(x) and wt(y) are distinct. Here, the weight of a vertex x in G is the sum of the label of x and the labels of all edges incident with the vertex x. The minimum k for which the graph G...