Timeline for A question on Borel measurability

9 events

when toggle format	what		by	license	comment
S Jul 11 at 4:39	history	edited	Tobias Fritz	CC BY-SA 4.0	improved the statements
S Jul 11 at 4:39	history	suggested	user532086	CC BY-SA 4.0	improved the statements
Jul 10 at 17:19	answer	added	David Gao		timeline score: 3
Jul 10 at 17:12	comment	added	David Gao		@TobiasFritz $\tau$ may not even be well-defined in that case, since there’s no reason $\{x \in X: \pi(x) = y\}$ is measurable.
Jul 10 at 13:41	review	Suggested edits
S Jul 11 at 4:39
Jul 10 at 13:06	comment	added	Tobias Fritz		Without further conditions, aren't there easy counterexamples obtained by equipping $Y = \{0,1\}$ with the indiscrete $\sigma$-algebra $\mathcal{B}_Y = \{\emptyset, Y\}$? Like this, every surjective $\pi$ is measurable, but $\tau$ is not unless it's constant.
Jul 10 at 12:46	history	edited	bobscott	CC BY-SA 4.0	added 43 characters in body; edited tags
S Jul 10 at 12:43	review	First questions
Jul 10 at 16:07
S Jul 10 at 12:43	history	asked	bobscott	CC BY-SA 4.0