The Hausdorff paradox is an incredibly counter-intuitive consequence of the axiom of choice; it is also important for demonstrating the non-existence, under AC, of a rotation-invariant measure on the discrete $\sigma$-algebra of the sphere.
But there is a part of the Hausdorff paradox that seems consistent with the existence of a rotation-invariant measure on the discrete $\sigma$-algebra, and yet still seems (to me) very counter-intuitive; so I am curious as to whether it can be proved without AC:
Is it a theorem of "ZF + Dependent Choice" that there exists a non-empty set $A \subset \mathbb{S}^2$ and rotations $R,R' \colon \mathbb{S}^2 \to \mathbb{S}^2$ such that $R(A)$ is disjoint from $A$ and $R'(A)=A \cup R(A)\,$?
Is it, at least, a theorem of "ZF + Dependent Choice" that there exists a non-empty set $A \subset \mathbb{S}^2$ and a rotation $R \colon \mathbb{S}^2 \to \mathbb{S}^2$ such that $A \subsetneq R(A)\,$?
(I fear there's some really obvious construction of such a set $A$ that I've missed - but I'll take the risk and ask the question!)