Obligatory subsystems of triple systems
نویسندگان
چکیده
We determine a class of triple systems such that each must occur in a triple system with uncountable chromatic number that omits T0 (the system consisting of two triples on four vertices). This class contains all odd circuit of length ≥ 7. We also show that consistently there are two finite triple systems such that they can separately be omitted by uncountably chromatic triple systems but not both.
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