It's known that ZF proves that for every set $x$ there exists a set $H_x$ of all sets that are hereditarily strictly subnumerous to $x$. [see [here\]][1]. Now is the following principle equivalent with choice over the rest of axioms of ZF? Every set $x$ is subnumerous to $H_x$. By "subnumerous to" its meant, as usual, possessing an injection towards; and "strictly subnumerous" means, as usual, existence of subnumerousity without existence of a bijection. [1]: https://randall-holmes.github.io/Drafts/hereditary.pdf