**EDIT**: The definition of a Suslin measurable set I wrote here is incorrect. It should be that $\mathcal{S}$ contains the *field* of open subsets of ${}^\omega\omega$. --- Recall that a *Suslin scheme* is a set of subsets of reals ${}^\omega\omega$ of the form: $$ \langle X_s : s \in {}^{<\omega}\omega\rangle $$ and that the *Suslin operation* $\mathcal{A}$ is an operation that takes a Suslin scheme $\mathcal{X} := \langle X_s : s \in {}^{<\omega}\omega\rangle$ and yield: $$ \mathcal{A}(\mathcal{X}) := \bigcap_{a \in {}^\omega\omega}\bigcup_{n \in \omega} X_{a\upharpoonright n} $$ The set of all **Suslin measurable sets**, call it $\mathcal{S}$, is the smallest set of subsets of reals such that: - $\mathcal{S}$ contains all open subsets of ${}^\omega\omega$. - $\mathcal{S}$ is closed under the Suslin operation (i.e. if $\mathcal{X}$ is a Suslin scheme in which $X_s \in \mathcal{S}$ for all $s$, then $\mathcal{A}(\mathcal{X}) \in \mathcal{S}$). --- A result of Nikodym says that the set of Baire subsets of reals is closed under the Suslin operation (Corollary 4.8 of Todorcevic's *Introduction to Ramsey spaces*). Thus, every Suslin measurable subset of reals has the Baire property. The questions I have are: 1. Can we prove, in $\mathsf{ZFC}$ and $\mathsf{ZF}$, that there exists a Baire subset of reals that is not Suslin measurable? 2. If it is not provable in $\mathsf{ZF}$, is there a well-known model of set theory in which every subset of reals is Suslin measurable? (Side question: There seems to be very little literature that discusses Suslin measurable sets. Is there another term for such sets?) **EDIT**: To clarify, a subset $X$ of real is Baire (or has the Baire property) if $X = U \, \triangle \, M$, where $U$ is open and $M$ is meagre.