I'm replacing in a *.tex file (e.g.) '\Omega' character definitions.

In the Unicode tables I find a lot of different "Omegas', but just
incoherent character set definitions and with different renderings
(depending on the output device some are taller, others are thiner).

Ω (U+03A9) (Greek and Coptic sets; Range: 0370–03FF)
Ω (U+2126) ohm sign

𝛀 (U+1D6C0) bold
𝛺 (U+1D6FA) italic
𝜴 (U+1D734) bold italic
𝝮 (U+1D76E) sans-serif bold
𝞨 (U+1D7A8) sans-serif bold italic

The first two are similar (or even the same?), the latter five seem
to have all the same dimensions (width/height) but there's no plain
version in that set[*]; so if you mix bold or italic with the plain
character in a text it looks like garbage.

What's the rationale behind such incoherent character definitions?
(Or what am I missing?)

Janis

[*] Defined in section "Mathematical Alphanumeric Symbols block" on
https://en.wikipedia.org/wiki/Mathematical_operators_and_symbols_in_Unicode

On 25/08/2023 21:26, Janis Papanagnou wrote:
> I'm replacing in a *.tex file (e.g.) '\Omega' character definitions.
>
> In the Unicode tables I find a lot of different "Omegas', but just
> incoherent character set definitions and with different renderings
> (depending on the output device some are taller, others are thiner).
>
> Ω (U+03A9) (Greek and Coptic sets; Range: 0370–03FF)

This what you use if you were writing Greek.

> Ω (U+2126) ohm sign

This is for electronics

>
> 𝛀 (U+1D6C0) bold
> 𝛺 (U+1D6FA) italic
> 𝜴 (U+1D734) bold italic
> 𝝮 (U+1D76E) sans-serif bold
> 𝞨 (U+1D7A8) sans-serif bold italic

IANAM, but maybe they have different meanings? And could coexist on the
same blackboard. Otherwise you could just have the font do the
bold/italic bit.

>
> The first two are similar (or even the same? tthe latter five seem > to have all the same dimensions (width/height) but there's no plain
> version in that set[*]; so if you mix bold or italic with the plain
> character in a text it looks like garbage.
>
> What's the rationale behind such incoherent character definitions?
> (Or what am I missing?)

Characters have a specific meaning, but could share or have a very
similar glyph. Like an umlaut and a diaeresis are different - they just
look the same.

In comp.unix.shell, Janis Papanagnou <janis_papanagnou+ng@hotmail.com> wrote:
> I'm replacing in a *.tex file (e.g.) '\Omega' character definitions.
>
> In the Unicode tables I find a lot of different "Omegas', but just
> incoherent character set definitions and with different renderings
> (depending on the output device some are taller, others are thiner).
>
> Ω (U+03A9) (Greek and Coptic sets; Range: 0370–03FF)
> Ω (U+2126) ohm sign
>
> 𝛀 (U+1D6C0) bold
> 𝛺 (U+1D6FA) italic
> 𝜴 (U+1D734) bold italic
> 𝝮 (U+1D76E) sans-serif bold
> 𝞨 (U+1D7A8) sans-serif bold italic

U+03A9 Ω GREEK CAPITAL LETTER OMEGA
U+2126 Ω OHM SIGN
U+1D6C0 𝛀 MATHEMATICAL BOLD CAPITAL OMEGA
U+1D6FA 𝛺 MATHEMATICAL ITALIC CAPITAL OMEGA
U+1D734 𝜴 MATHEMATICAL BOLD ITALIC CAPITAL OMEGA
U+1D76E 𝝮 MATHEMATICAL SANS-SERIF BOLD CAPITAL OMEGA
U+1D7A8 𝞨 MATHEMATICAL SANS-SERIF BOLD ITALIC CAPITAL OMEGA

> The first two are similar (or even the same?), the latter five seem
> to have all the same dimensions (width/height) but there's no plain
> version in that set[*]; so if you mix bold or italic with the plain
> character in a text it looks like garbage.

The Greek one is the one to use for Greek text and for general "capital
Omega". The ohm sign is to use for electronics. The others are all
reserved for mathematical contexts where bold/italic/whatever is part of
a symbol's name not part of the overall document styling.

I don't know what \Omega is in Tex, but I'm betting it is supposed to be
the capital Greek letter.

> What's the rationale behind such incoherent character definitions?

To the extent that Unicode has _variations_ on a character, those
variations are meant to convey a different meaning. Mathematicians are
just notorious for running out of symbols and ransacking other languages
and/or making up new ones through "style" changes.

Elijah
------
see also U+05D0 and U+2135

Janis Papanagnou <janis_papanagnou+ng@hotmail.com> writes:
> I'm replacing in a *.tex file (e.g.) '\Omega' character definitions.
>
> In the Unicode tables I find a lot of different "Omegas', but just
> incoherent character set definitions and with different renderings
> (depending on the output device some are taller, others are thiner).
>
> Ω (U+03A9) (Greek and Coptic sets; Range: 0370–03FF)
> Ω (U+2126) ohm sign
>
> 𝛀 (U+1D6C0) bold
> 𝛺 (U+1D6FA) italic
> 𝜴 (U+1D734) bold italic
> 𝝮 (U+1D76E) sans-serif bold
> 𝞨 (U+1D7A8) sans-serif bold italic
>
> The first two are similar (or even the same?), the latter five seem
> to have all the same dimensions (width/height) but there's no plain
> version in that set[*]; so if you mix bold or italic with the plain
> character in a text it looks like garbage.
>
> What's the rationale behind such incoherent character definitions?
> (Or what am I missing?)
>
> Janis
>
> [*] Defined in section "Mathematical Alphanumeric Symbols block" on
> https://en.wikipedia.org/wiki/Mathematical_operators_and_symbols_in_Unicode

There's some discussion here: <https://tex.stackexchange.com/q/32337>.

I'm not a TeX user, so I can't really comment further.

--
Keith Thompson (The_Other_Keith) Keith.S.Thompson+u@gmail.com
Will write code for food.
void Void(void) { Void(); } /* The recursive call of the void */

On Fri, 25 Aug 2023 22:26:41 +0200
Janis Papanagnou <janis_papanagnou+ng@hotmail.com> wrote:
> I'm replacing in a *.tex file (e.g.) '\Omega' character definitions.

For (la)tex questions there exists comp.tex.text , for general Unicode
questions probably comp.misc would be the most appropriate.

Anyway , you are replacing the character definitions with what and why ?
What are you trying to achieve ?

> In the Unicode tables I find a lot of different "Omegas', but just
> incoherent character set definitions and with different renderings
> (depending on the output device some are taller, others are thiner).
>
> Ω (U+03A9) (Greek and Coptic sets; Range: 0370–03FF)
> Ω (U+2126) ohm sign
>
> 𝛀 (U+1D6C0) bold
> 𝛺 (U+1D6FA) italic
> 𝜴 (U+1D734) bold italic
> 𝝮 (U+1D76E) sans-serif bold
> 𝞨 (U+1D7A8) sans-serif bold italic
>
> The first two are similar (or even the same?),

Whether they look the same is a decision of the font designers. They are
not the same either culturally or as codepoints. If a tex document has
\Omega then it means that the person who wrote it wanted a capital Greek
omega.

> the latter five seem
> to have all the same dimensions (width/height) but there's no plain
> version in that set[*]; so if you mix bold or italic with the plain
> character in a text it looks like garbage.

How it looks has more to do with the font design rather than Unicode.
Perhaps try a different font ? And why would you want to mix them ?

I've never used tex directly but with latex the idea is that you
specify stuff at a higher level and you let latex handle the
typography like choice of fonts. So why are you even working at such
a low level ?

> What's the rationale behind such incoherent character definitions?
> (Or what am I missing?)
>
> Janis
>
> [*] Defined in section "Mathematical Alphanumeric Symbols block" on
> https://en.wikipedia.org/wiki/Mathematical_operators_and_symbols_in_Unicode

On Sat, 26 Aug 2023 11:05:37 -0000 (UTC)
Spiros Bousbouras <spibou@gmail.com> wrote:
> On Fri, 25 Aug 2023 22:26:41 +0200
> Janis Papanagnou <janis_papanagnou+ng@hotmail.com> wrote:
> > I'm replacing in a *.tex file (e.g.) '\Omega' character definitions.
>
> For (la)tex questions there exists comp.tex.text , for general Unicode
> questions probably comp.misc would be the most appropriate.

Make that comp.text.tex .

On Sat, 26 Aug 2023 01:52:32 -0000 (UTC), Eli the Bearded
<*@eli.users.panix.com> wrote:

> Mathematicians are just notorious for running
> out of symbols and ransacking other languages
> and/or making up new ones through "style" changes.

Can't they be trained to just write Fortran instead?

:-)

--
Kees Nuyt

On 26.08.2023 03:52, Eli the Bearded wrote:
> In comp.unix.shell, Janis Papanagnou <janis_papanagnou+ng@hotmail.com> wrote:
>> I'm replacing in a *.tex file (e.g.) '\Omega' character definitions.
>>
>> In the Unicode tables I find a lot of different "Omegas', but just
>> incoherent character set definitions and with different renderings
>> (depending on the output device some are taller, others are thiner).
>>
>> Ω (U+03A9) (Greek and Coptic sets; Range: 0370–03FF)
>> Ω (U+2126) ohm sign
>>
>> 𝛀 (U+1D6C0) bold
>> 𝛺 (U+1D6FA) italic
>> 𝜴 (U+1D734) bold italic
>> 𝝮 (U+1D76E) sans-serif bold
>> 𝞨 (U+1D7A8) sans-serif bold italic
>
> U+03A9 Ω GREEK CAPITAL LETTER OMEGA
> U+2126 Ω OHM SIGN
> U+1D6C0 𝛀 MATHEMATICAL BOLD CAPITAL OMEGA
> U+1D6FA 𝛺 MATHEMATICAL ITALIC CAPITAL OMEGA
> U+1D734 𝜴 MATHEMATICAL BOLD ITALIC CAPITAL OMEGA
> U+1D76E 𝝮 MATHEMATICAL SANS-SERIF BOLD CAPITAL OMEGA
> U+1D7A8 𝞨 MATHEMATICAL SANS-SERIF BOLD ITALIC CAPITAL OMEGA
>
>> The first two are similar (or even the same?), the latter five seem
>> to have all the same dimensions (width/height) but there's no plain
>> version in that set[*]; so if you mix bold or italic with the plain
>> character in a text it looks like garbage.
>
> The Greek one is the one to use for Greek text and for general "capital
> Omega". The ohm sign is to use for electronics. The others are all
> reserved for mathematical contexts where bold/italic/whatever is part of
> a symbol's name not part of the overall document styling.
>
> I don't know what \Omega is in Tex, but I'm betting it is supposed to be
> the capital Greek letter.

In my case it's a German text with occasional mathematical notations;
the \Omega is part of the latter (the mathematical formulas) here.

>
>> What's the rationale behind such incoherent character definitions?
>
> To the extent that Unicode has _variations_ on a character, those
> variations are meant to convey a different meaning. Mathematicians are
> just notorious for running out of symbols and ransacking other languages
> and/or making up new ones through "style" changes.

So the five mathematical variants have an own meaning each? - Okay, I
can't tell. I still just wonder (if the are "running out of symbols"!)
why they don't have a "plain" 'MATHEMATICAL CAPITAL OMEGA' defined.

(In practice I am using the "GREEK CAPITAL LETTER OMEGA" now for the
mathematical formulas. Mixing with other "MATHEMATICAL ..." entities
looks a bit weird now with their differing sizes, but okay.)

Thanks to all who replied.

Janis

Janis Papanagnou wrote:
>
> I'm replacing in a *.tex file (e.g.) '\Omega' character definitions.
>
> In the Unicode tables I find a lot of different "Omegas', but just
> incoherent character set definitions and with different renderings
> (depending on the output device some are taller, others are thiner).
>
> Ω (U+03A9) (Greek and Coptic sets; Range: 0370–03FF)
> Ω (U+2126) ohm sign

Quoted from the Unicode 15 database (UnicodeData.txt):
<https://www.unicode.org/Public/15.0.0/ucd/>
|
| [...]
| 03A9;GREEK CAPITAL LETTER OMEGA;Lu;0;L;;;;;N;;;;03C9;
| [...]
| 2126;OHM SIGN;Lu;0;L;03A9;;;;N;OHM;;;03C9;
^^^^
The field with index 5 contains the decomposition mapping:
<https://www.unicode.org/reports/tr44/#UnicodeData.txt>
<https://www.unicode.org/reports/tr44/#Character_Decomposition_Mappings>
|
| The prefixed tags supplied with a subset of the decomposition mappings
| generally indicate formatting information. Where no such tag is given,
| the mapping is canonical. [...]

U+2126 has a singleton decomposition to U+03A9 and therefore will not
survive normalization. Both are canonically equivalent.