ULTRA-COMBINATORICS. Applications of ultrafilters in combinatorial number theory, and related topics
timetable:
Thu 24 Jan, 10:30 - 11:30, Aula Dini
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Addition and multiplication in $\beta$N
speaker: Dona Strauss (University of Leeds)abstract: The operations of addition and multiplication on N both extend to $\beta$N. The relationship between these operations in $\beta$N has given rise to important new theorems in combinatorics. I shall present a proof that the closure of the set of multiplicative idempotents in $\beta$N does not meet the set of additive idempotents in $\beta$N. So there is no additive idempotent $p$ in $\beta$N with the property that every member of $p$ contains all the finite products of some infinite sequence in N.
timetable:
Thu 24 Jan, 10:30 - 11:30, Aula Dini
<< Go back