Is this a U?

Hi all

The attached are taken from Frege's Grundgesetze der Arithmetik
(Jenna, Germany 1893). Athough the symbol on the middle of the
second line looks like a U, the vertical strokes seem to me to
be too close together; I thought it might be a commercial sign
like the "per" symbol (unicode U-214C).

I'd be most grateful if anyone could tell me more about it.

Thanks in advance



May be the old symbol for “Union” in set theory?

Conor, I don't think it is a union symbol since
that was only introduced in 1888 (by Peano) and
was without ductus, rather like the modern form.


I thought it might be "Not-greater-than", U+226F, ≯, but that' can't follow '=', as it does in the second line.


Perhaps an early (or Frege’s) way of symbolising “universal quantification” or “∀”.