Tagged Questions
3
votes
3answers
63 views
What are the sets $S_n=\omega-n$ called?
What are the sets $S_n$ where $S_n:=\omega-n$ called?
I explain better: if ordinals are defined in this way
$0=\varnothing$
$1=\{\varnothing\}=\{0\}$
$2=\{0,1\}$
$n=\{0,1,..,n-1\}$
...
2
votes
2answers
131 views
What is the name of $V_\alpha$?
In the Von Neumann cumulative hierarchy, $V:=\bigcup_\alpha(V_\alpha)$ is called the universe. Is there a name for the individual levels $V_\alpha$?
Just as one can say "The closure of $A$ is defined ...
2
votes
1answer
90 views
What is this function on ordinals called?
Define a function $f:\mathbf{ON}\to\mathbf{ON}$ as follows: for each ordinal number $\alpha$ let $$f(\alpha)=\operatorname{ord(}\lbrace \beta<\alpha|\text{ }\beta\textrm{ is a limit ...
