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SUMMARY:Subseries numbers for convergent subseries - Tristan van der Vlugt
  (Technische Universität Wien)
DTSTART:20241122T150000Z
DTEND:20241122T160000Z
UID:TALK224353@talks.cam.ac.uk
CONTACT:Benedikt Loewe
DESCRIPTION:An infinite series of real numbers is conditionally convergent
  if it converges\, but the sums of the positive and of the negative terms 
 are both divergent. How many infinite subsets of the naturals are necessar
 y such that every conditionally convergent series has a subseries given by
  one of our infinite subsets that is divergent? The answer to this questio
 n is known as the subseries number ß\, and was isolated as a cardinal cha
 racteristic of the continuum by Brendle\, Brian and Hamkins.\n\nIn this ta
 lk we will consider several variants of the subseries number\, where we re
 strict our attention to infinite subsets of the naturals that are also coi
 nfinite. Due to this change\, we\nmay consider subseries produced by infin
 ite coinfinite subsets of the naturals that remain convergent\, producing 
 various closely related cardinal characteristics of the continuum.
LOCATION:Centre for Mathematical Sciences\, MR14
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