Search results with tag "Introduction to topology"

Introduction to Topology - Department of Mathematics

– Let’s just check for two subsets U 1;U 2 first. For each x 2U 1 \U 2, there are B 1;B 2 2Bsuch that x 2B 1 ˆU 1 and x 2B 2 ˆU 2.This is because U 1;U 2 2T Band x 2U 1;x 2U 2.By (B2), there is B 3 2Bsuch that x 2B 3 ˆB 1 \B 2.Now we found B 3 2Bsuch that x 2B 3 ˆU. – We can generalize the above proof to n subsets, but let’s use induction to prove it.

  Department, Introduction, Topology, Introduction to topology