1,760 research outputs found
On DP-Coloring of Digraphs
DP-coloring is a relatively new coloring concept by Dvo\v{r}\'ak and Postle
and was introduced as an extension of list-colorings of (undirected) graphs. It
transforms the problem of finding a list-coloring of a given graph with a
list-assignment to finding an independent transversal in an auxiliary graph
with vertex set . In this paper, we
extend the definition of DP-colorings to digraphs using the approach from
Neumann-Lara where a coloring of a digraph is a coloring of the vertices such
that the digraph does not contain any monochromatic directed cycle.
Furthermore, we prove a Brooks' type theorem regarding the DP-chromatic number,
which extends various results on the (list-)chromatic number of digraphs.Comment: 23 pages, 6 figure
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Development of Nanocomposite Powders for the SLS Process to Enhance Mechanical Properties
In an effort to fabricate prototypes with improved mechanical properties in the dual laser
sintering process, functionalized graphite nanoplatelets were added to the PA-12 powder to
produce a nanocomposite powder. The PA-12 powder was chosen as the matrix polymer
because it has features conducive to laser sintering such as relatively low melting temperature
and high mechanical properties. The GNPs were oxidized through a nitric acid treatment to
improve the interfacial bonding. The resulting nanocomposite powder was layered and sintered
by laser without any sign of agglomeration. Although the result is preliminary, it nevertheless
shows the suitability of the nanocomposite powder for the laser sintering process.Mechanical Engineerin
Cisgenic overexpression of cytosolic glutamine synthetase improves nitrogen utilization efficiency in barley and prevents grain protein decline under elevated CO<sub>2</sub>
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