M. Gionfriddo, E. Guardo, L. Milazzo
Published 2011-06-09, updated 2013-08-30Version 3
We initiate the study of extended bicolorings of Steiner triple systems (STS) which start with a $k$-bicoloring of an STS($v$) and end up with a $k$-bicoloring of an STS($2v+1$) obtained by a doubling construction, using only the original colors used in coloring the subsystem STS($v$). By producing many such extended bicolorings, we obtain several infinite classes of orders for which there exist STSs with different lower and upper chromatic number.
Comments: We replace the old version "Extended colorings for $BSTS(2v+1)$"; the related appendix is arxiv:1308.4793. To appear in Applicable Analysis and Discrete Mathematics
Appendix of Extending Bicoloring for Steiner Triple Systems
The $k^{\text th}$ Upper Chromatic Number of the Line
Approximability of the upper chromatic number of hypergraphs
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