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  • Author or Editor: P. Hajnal x
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Abstract  

We determine a class of triple systems such that each must occur in a triple system with uncountable chromatic number that omits

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(the unique system consisting of two triples on four vertices). This class contains all odd circuits 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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In this column Periodica Mathematica Hungarica publishes current research problems whose proposers believe them to be within reach of existing methods. Manuscripts should preferably contain the background of the problem and all references known to the author. The length of the manuscript should not exceed two doublespaced typewritten pages.

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