MathDB
Finite number of Borel sets

Source: Miklós Schweitzer P10

September 9, 2020
topology

Problem Statement

Consider the space {0,1}N \{0,1 \} ^{N} with the product topology (where {0,1}\{0,1 \} is a discrete space). Let T:{0,1}N{0,1}N T: \{0,1 \} ^ {\mathbb {N}} \rightarrow \{0,1 \} ^ {\mathbb {N}} be the left-shift, ie (Tx)(n)=x(n+1) (Tx) (n) = x (n+1) for every nN n \in \mathbb {N} . Can a finite number of Borel sets be given: B1,,Bm{0,1}N B_ {1}, \ldots, B_ {m} \subset \{0,1 \} ^ {N} such that {Ti(Bj)iN,1jm} \left \{T ^ {i} \left (B_ {j} \right) \mid i \in \mathbb {N}, 1 \leq j \leq m \right \} the σ \sigma -algebra generated by the set system coincides with the Borel set system?