A combinatorial property of Frechet iterated filters

作者：Debs Gabriel; Saint Raymond Jean^*

来源：Topology and Its Applications, 2012, 159(8): 2205-2227.

DOI：10.1016/j.topol.2012.03.004

• Borel filters
• Borel functions
• Baire classes

For all m >= 1 let N-m be the filter on omega(m) obtained from the Frechet filter on omega by iterating the Fubini product operation. One easily checks that N-m is a Sigma(0)(2m) subset of P(omega(m)) and the main result of this work states that in any Pi(0)(2m) subset of P(wm) containing N-m one can find m + 1 elements with empty intersection.

• 出版日期2012-5-15