Let's say a set $x$ is super-singular, if and only if, $| \bigcup x| > |x|$, and for each $y \in x$ we have: $ |y| \not > |x|$ . A set $x$ is hyper-singular, if and only if, $| \bigcup x| > |x|$, and for each $y \in x$ we have: $|y| \not > |x| \land |y| \neq |x|$. A set $x$ is ultra-singular, if and only if, $| \bigcup x| > |x|$, and for each $y \in x$ we have: $|y| < |x|$. Finite examples include $\{\{0\},\{1,2\}\}$ being super-singular, and $\{ \{0 \} , \{1\}, \{2,3\} \}$ being ultra-singular. Infinite examples of ultra-singular includes Russell's sock. > Is it equivalent to AC to say that no super-singlular set exists? > Which of the known choice principles non-existence of the other two kinds of sets is equivalent to?