Well, U+2206 (INCREMENT) is the only correctly oriented triangle I see in the
Mathematical Operators block (https://codepoints.net/mathematical_operators).
The U+25B3 (WHITE UP-POINTING TRIANGE) is part of the Geometric Shapes block
(https://codepoints.net/geometric_shapes).

Looking at the individual pages for each character:

- https://codepoints.net/U+2206, and
- https://codepoints.net/U+25B3,

codepoints.net does claim that U+2206 is used for set symmetric difference.
That said, U+25B3 certainly looks a lot more symmetric in the typeface it's
rendering as on my machine.

Each page also gives a nice set of "confusables." Each of the above two
characters lists the other in that section. How about U+1F702 (ALCHEMAL
SYMBOL FOR FIRE) though! ;p

Benoit <[email protected]> wrote:
> I proposed the symbol for symmetric difference in 
> https://github.com/metamath/set.mm/pull/1613#issuecomment-619592865 , 
> namely U+25B3, after a quick google search for "unicode triangle". On the 
> html pages, it looks a bit too large (ideally, it should be the same size 
> as for \cap and \cup, especially the lower horizontal line).  But I cannot 
> find the exact unicode for $\triangle$.  The wikipedia page just cited is 
> wrong: the symbol used in the first column corresponds to the LaTeX 
> \triangle, but the columns "HTML" and "Unicode" correspond to other symbols.
> 
> (By the way: since the symmetric difference is commutative, it's nice to 
> have a left-right symmetric symbol, so \Delta is not good.)
> 
> Benoît
> 
> 
> On Monday, April 27, 2020 at 8:15:05 AM UTC+2, [email protected] wrote:
> >
> > FWIW, this Wikipedia list corresponds TeX's \triangle with U+2206: 
> > https://en.wikipedia.org/wiki/List_of_mathematical_symbols_by_subject 
> > Mario Carneiro <[email protected] <javascript:>> wrote: 
> > > I'm not so sure about that. It looks like the primary meaning of that 
> > > codepoint is "increment operator", used for small discrete changes, 
> > which 
> > > usually is an actual Delta (and read as such aloud). Visually, it also 
> > > shows the same typographic weight changes as is common with Delta that 
> > are 
> > > absent in the white triangle symbol. 
> > > 
> > > As for using the triangle symbol for geometry, well let's just say 
> > that's a 
> > > conversation for another day. 
> > > 
> > > 
> > > On Sun, Apr 26, 2020 at 10:12 PM Thierry Arnoux <[email protected] 
> > <javascript:>> 
> > > wrote: 
> > > 
> > > > You’re right! Actually, the code I used is x2206, which is listed as 
> > > > “Symmetrical Difference”, so I believe it shall be the correct one. 
> > > > https://codepoints.net/U+2206 
> > > > 
> > > > This is a different code from Uppercase Delta (code x394), I wanted to 
> > > > describe the shape - thanks for correcting me! 
> > > > 
> > > > We can still use the x25B3 code (triangle) for geometry! ;-) 
> > > > BR, 
> > > > _ 
> > > > Thierry 
> > > > file:///home/benoit/T%C3%A9l%C3%A9chargements/test.html
> > > > 
> > > > Le 27 avr. 2020 à 11:44, Mario Carneiro <[email protected] 
> > <javascript:>> a écrit : 
> > > > 
> > > >  
> > > > I think there is a unicode symbol for symmetric difference that is a 
> > white 
> > > > upward pointing triangle (U+25B3 △), not an upper case Delta (which 
> > looks a 
> > > > bit different due to weight changes along the glyph). 
> > > > 
> > > > -- 
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> >  
> > > > <
> > https://groups.google.com/d/msgid/metamath/08094638-8C7B-47D9-814C-4E621E5C5B94%40gmx.net?utm_medium=email&utm_source=footer>
> >  
> >
> > > > . 
> > > > 
> >
> >


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