Long-distance telephone companies in the United States (U.S.) pay access fees to local telephone companies to transport calls that originate and terminate on their networks. These charges form the largest portion of the cost of providing long-distance service. Recent changes in the structure of access rates, which were mandated by the Federal Communications Commission (FCC), have created opport...

We explore the relationship between R. W. Shephard's input distance function (``Cost and Production Functions,'' Princeton Univ. Press, Princeton, 1953) and D. G. Luenberger's benefit function (J. Math. Econ. 21 (1992a), 461 481). We point out that the latter can be recognized in a production context as a directional input distance function which can exhaustively characterize technologies in bo...

genetic variation of 20 genotypes (15 exotic collected from icarda, and 5 endemic collected from various regions of iran: ardebil, oshnaviyeh, qazvin, shahre kord and mashhad) were studied during the 2007-2008 growing season, using morphological and phenological traits. the resultant data were examined for normality test and were then analyzed according to randomized complete block design (rcbd...

a set $s$ of vertices in a graph $g=(v,e)$ is called a total$k$-distance dominating set if every vertex in $v$ is withindistance $k$ of a vertex in $s$. a graph $g$ is total $k$-distancedomination-critical if $gamma_{t}^{k} (g - x) < gamma_{t}^{k}(g)$ for any vertex $xin v(g)$. in this paper,we investigate some results on total $k$-distance domination-critical of graphs.