# the Powerset Symbol

• To: math-font-discuss@cogs.susx.ac.uk
• Subject: the Powerset Symbol
• From: Justin Ziegler <ziegler@goofy.zdv.uni-mainz.de>
• Date: Thu, 19 Aug 1993 12:00:43 +0000

In message <AA24435.9308170941.ws-csm3@uk.ac.durham> you write:
>
>I have done some more research on the powerset question. This is a rough
>representation of the symbol I have in mind, which I will call "open P":
>
>          XXXXXXXXXXX
>      XXXXXXXX    XXXX
>    XXXXX           XXXX
>    XXXXX           XXXX
>  XXXXXXXX          XXXX
>  XXX  XXX          XX
>  XX   XXXXXXX  XXXXXX
>  XX    XXXXXXXXXXXX
>  XX    XXXX
>  XX    XXXX
>  XX      XXXX
>  XX      XXXX
>  XXXX    XXXX
>  XXXX    XXXX
>  XXXX  XXXX
>    XXXXXX
>
>(This ascii representation assumes a 2:1 aspect ratio on your terminal!)
>(Imagine it drawn with a single smooth stroke of the pen).
>
>The following books use the open P for powerset:
>
>R.R.Stoll "Set theory and Logic", W.H.Freeman & Co, 1961,1963, P.11
>
>P.Suppes "Axiomatic Set Theory", D.Van Nostrand Co, 1960
>
>
>The following use a script P (similar to the one in Ralph Smith's Formal
>Script font, rsfs10):
>
>B.Rotman & G.T.Kneebone "The Theory of Sets and Transfinite Numbers",
>Oldbourne, 1966, P.46
>
>H.Rubin & J.Rubin "Equivalents of the Axiom of Choice", North Holland, 1963
>
(of course, this is confusing if you want to use script letters for classes)
>
>
>I have also seen a "blackboard bold P" used for this purpose.
>
>
>I hope this is of some value.
>

so we have quite a few references for the powerset symbol. If include it,
it will go next to the \wr, and the \ell, ei latin friends. Is that OK?

Second question: should I include it at all ? Is it not just an other
style of the \wr, or just a script P or p, or cursive P or p ? in which
case it lives in the corresponding alphabet ?

JZ

Ps: this is the type of question I like to have more than one answer, so
that I can get an idea of what people think.