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6 papers · 1 filter
Research problem: The completion number of a graph
M. Bakonyi, T. Constantinescu
Motivated by the remarkable interplay between (chordal) graphs and matrix algebra, we associate to each graph a so-called completion number that might encode some aspects of that i…
The Structure of F-Pure Rings
Ian M. Aberbach, Florian Enescu
For a reduced F-finite ring R of characteristic p >0 and q=p^e one can write R^{1/q} = R^{a_q} \oplus M_q, where M_q has no free direct summands over R. We investigate the structur…
Emission Line Properties of AGN from a post-COSTAR FOS HST Spectral Atlas
J. K. Kuraszkiewicz, P. J. Green, D. M. Crenshaw +4
This paper joins a series compiling consistent emission line measurements of large AGN spectral databases, useful for reliable statistical studies of emission line properties. It i…
Two New Close Binary Central Stars of Planetary Nebulae from a Critically Selected Southern Hemisphere Sample
Todd C. Hillwig
I present the results of time-resolved photometry of a selection of central stars of planetary nebulae. The study reveals periodic variability in two of the eight central stars obs…
P is not equal to NP intersect coNP for Infinite Time Turing Machines
Vinay Deolalikar, Joel David Hamkins, Ralf-Dieter Schindler
Extending results of Schindler [math.LO/0106087] and Hamkins and Welch [math.LO/0212046], we establish in the context of infinite time Turing machines that P is properly contained…
Radio Galaxies and the Magnetization of the IGM
Gopal-Krishna, Paul J. Wiita
Observed radio galaxies had a much higher comoving density during the `quasar era', at z ~ 2-3, but these sources are only detectable for small fractions of their active lifetimes…