A graph G is a Zm-well-covered graph if |I1| ≡ |I2| (modm) for all maximal independent sets I1 and I2 in V (G) [3]. The recognition problem of Zm-well-covered graphs is a Co-NP-Complete problem. We give a characterization of Zm-well-covered graphs for chordal, simplicial and circular arc graphs. c © 2001 Elsevier Science B.V. All rights reserved.

the activation of carbon monoxide by oxygen on mg(100) surface has been investigated by x-ray photoelectron spectroscopy (xps). carbon monoxide is only weakly adsorbed (dispersion-type forces) on a magnesium surface. the xps result has shown that the dissociation of carbon monoxide leading to the formation of a metastable surface carbonate species occurs through the participation of an oxygen s...

â â â â â  abstract: â  as the number of independent countries increases and their economies become more integrated, we would expect to observe more multi-country currency ::::union::::s. this paper explores the pros and cons for different countries to adopt as an anchor the us dollar, the euro or the yen. in addition, it addresses the question of how co-movement of outputs and prices would res...

air pollution in large cities is very important from health and economic points of views. in a city, air pollution has direct relationship with the topography, climate, population, economic situation and the degree of industrialization. therefore, for a survey about kerman's air pollution, 13 stations were chosen for determination of so2, no2 and co, and 14 stations to assess concentration of s...

biv is a well-known bovine immunosup-pressive cause, but its pathogenesis has not been well characterized. it seems that it is possible that cofactors such as co- infection with other bovine viral pathogens may play a role in enhancing the pathogenesis of biv infection; bvdv also has immunosuppressive effects. objective: the aim of this study was determination of possible correlation between bi...

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in this paper, a new molecular-structure descriptor, the general sum–connectivity co–index  is considered, which generalizes the first zagreb co–index and the general sum–connectivity index of graph theory. we mainly explore the lower and upper bounds in termsof the order and size for this new invariant. additionally, the nordhaus–gaddum–type resultis also represented.