Comparing the expressibility of two languages formed using NP-complete graph operators

Author(s):  
Iain A. Stewart
Keyword(s):  
2010 ◽  
Vol 21 (03) ◽  
pp. 311-319 ◽  
Author(s):  
AYSUN AYTAC ◽  
ZEYNEP NIHAN ODABAS

The rupture degree of an incomplete connected graph G is defined by [Formula: see text] where w(G - S) is the number of components of G - S and m(G - S) is the order of a largest component of G - S. For the complete graph Kn, rupture degree is defined as 1 - n. This parameter can be used to measure the vulnerability of a graph. Rupture degree can reflect the vulnerability of graphs better than or independent of the other parameters. To some extent, it represents a trade-off between the amount of work done to damage the network and how badly the network is damaged. Computing the rupture degree of a graph is NP-complete. In this paper, we give formulas for the rupture degree of composition of some special graphs and we consider the relationships between the rupture degree and other vulnerability parameters.


1977 ◽  
Vol 9 (3) ◽  
pp. 24-24 ◽  
Author(s):  
M. S. Krishnamoorthy

1976 ◽  
Vol 1 (3) ◽  
pp. 237-267 ◽  
Author(s):  
M.R. Garey ◽  
D.S. Johnson ◽  
L. Stockmeyer

2018 ◽  
Vol 27 (5) ◽  
pp. 808-828 ◽  
Author(s):  
LEONID A. LEVIN ◽  
RAMARATHNAM VENKATESAN

NP-complete problems should be hard on some instances but those may be extremely rare. On generic instances many such problems, especially related to random graphs, have been proved to be easy. We show the intractability of random instances of a graph colouring problem: this graph problem is hard on average unless all NP problems under all samplable (i.e. generatable in polynomial time) distributions are easy. Worst case reductions use special gadgets and typically map instances into a negligible fraction of possible outputs. Ours must output nearly random graphs and avoid any super-polynomial distortion of probabilities. This poses significant technical difficulties.


2009 ◽  
Vol 69 (3) ◽  
pp. 221-229 ◽  
Author(s):  
Israel Marck Martínez-Pérez ◽  
Karl-Heinz Zimmermann

1978 ◽  
Vol 9 (4) ◽  
pp. 17-17 ◽  
Author(s):  
M. R. Garey ◽  
D. S. Johnson

Mathematics ◽  
2019 ◽  
Vol 8 (1) ◽  
pp. 17 ◽  
Author(s):  
Abdollah Alhevaz ◽  
Maryam Baghipur ◽  
Hilal A. Ganie ◽  
Yilun Shang

The generalized distance matrix D α ( G ) of a connected graph G is defined as D α ( G ) = α T r ( G ) + ( 1 − α ) D ( G ) , where 0 ≤ α ≤ 1 , D ( G ) is the distance matrix and T r ( G ) is the diagonal matrix of the node transmissions. In this paper, we extend the concept of energy to the generalized distance matrix and define the generalized distance energy E D α ( G ) . Some new upper and lower bounds for the generalized distance energy E D α ( G ) of G are established based on parameters including the Wiener index W ( G ) and the transmission degrees. Extremal graphs attaining these bounds are identified. It is found that the complete graph has the minimum generalized distance energy among all connected graphs, while the minimum is attained by the star graph among trees of order n.


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