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Simple Signed Steiner Triple Systems
Authors:E Ghorbani  G B Khosrovshahi
Institution:1. Department of Mathematics, K. N. Toosi University of Technology, , Tehran, Iran;2. School of Mathematics, Institute for Research in Fundamental Sciences (IPM), , Tehran, Iran;3. Department of Mathematics, Statistics and Computer Science, University of Tehran, , Iran
Abstract:Let X be a v‐set, urn:x-wiley:10638539:jcd21297:equation:jcd21297-math-0001 be a set of 3‐subsets (triples) of X, and urn:x-wiley:10638539:jcd21297:equation:jcd21297-math-0002 be a partition of urn:x-wiley:10638539:jcd21297:equation:jcd21297-math-0003 with urn:x-wiley:10638539:jcd21297:equation:jcd21297-math-0004. The pair urn:x-wiley:10638539:jcd21297:equation:jcd21297-math-0005 is called a simple signed Steiner triple system, denoted by STurn:x-wiley:10638539:jcd21297:equation:jcd21297-math-0006, if the number of occurrences of every 2‐subset of X in triples urn:x-wiley:10638539:jcd21297:equation:jcd21297-math-0007 is one more than the number of occurrences in triples urn:x-wiley:10638539:jcd21297:equation:jcd21297-math-0008. In this paper, we prove that urn:x-wiley:10638539:jcd21297:equation:jcd21297-math-0009 exists if and only if urn:x-wiley:10638539:jcd21297:equation:jcd21297-math-0010, urn:x-wiley:10638539:jcd21297:equation:jcd21297-math-0011, and urn:x-wiley:10638539:jcd21297:equation:jcd21297-math-0012, where urn:x-wiley:10638539:jcd21297:equation:jcd21297-math-0013 and for urn:x-wiley:10638539:jcd21297:equation:jcd21297-math-0014, urn:x-wiley:10638539:jcd21297:equation:jcd21297-math-0015. © 2012 Wiley Periodicals, Inc. J. Combin. Designs 20: 332–343, 2012
Keywords:simple signed Steiner triple system  trade
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