What symbol is this?

Question

Symbol

I need the command to display this symbol in LaTeX or, at least, its name.

I guess it’s from some kind of a mathematical or informatics discipline. I saw it in article called “A comparison of collapsed Bayesian methods for probabilistic finite automata”. Actually, I have no idea what it is all about: I just started learning LaTeX and I have to copy this article. This symbol is used just as if it is a casual letter like x or y. The line which includes it is,

Input : a(this symbol), N, BurnInTime, SamplingNum, Period

Welcome to tex.sx! Where did you see this symbol, what does it mean, what field of study does it belong to? — doncherry, Jul 02 '14 at 13:24
I have never seen this symbol before. Have you checked the comprehensive symbol list already? http://mirrors.ctan.org/info/symbols/comprehensive/symbols-a4.pdf — , Jul 02 '14 at 13:29
I guess it's from some kind of a math or informatic discipline, saw it in article called "A comparison of collapsed Bayesian methods for probabilistic finite automata". Actually, i have no idea what is it all about, i just started learning LaTeX and i have to copy this article. This symbol is used just like it's a casual letter like "x" or "y". Line with it looks like "Input : a(this symvol), N, BurnInTime, SamplingNum, Period — Igor, Jul 02 '14 at 13:34
If that article is made in LaTeX too, chances are good, that the symbol is available too — , Jul 02 '14 at 13:35
the article is in Machine Learning (2014) 96:155-188, published by springer, so maybe it was prepared in latex. unfortunately, only the abstract and introduction are posted at the link, and they don't show the symbol (which i've never seen before either). — barbara beeton, Jul 02 '14 at 13:47
try http://detexify.kirelabs.org/ or look a http://arxiv.org/ for an article containing this symbol and than under other formats->download source to view the .tex code — samcarter_is_at_topanswers.xyz, Jul 02 '14 at 13:53
possible duplicate of How to look up a symbol or identify a math alphabet? — Martin Schröder, Jul 02 '14 at 14:54
@MartinSchröder If it is not possible to find via tools in that question we tend to leave these open, with emphasis on tend to — percusse, Jul 02 '14 at 15:04
@MartinSchröder -- that's a great question and answers, but not one of them addresses the method that was needed to identify this particular symbol. if someone would add to those answers the method for checking what fonts are used in a known pdf file, that would improve that question almost to the point where this could be considered a duplicate. — barbara beeton, Jul 02 '14 at 15:05
@samcarter detexify.kirelabs.org didn't find the letter (or symbol) and that I tried to draw it as best I could. — skpblack, Jul 02 '14 at 15:28

score 25 · Accepted Answer · edited Apr 13 '17 at 12:34

25

To me this looks like a blackboard bold lowercase a. Specifically, it looks like the lowercase a from the bbold font.

bbold font

For blackboard bold capitals you can use the \mathbb macro provided by the amsfonts or amssymb packages. But $\mathbb{a}$ gives a backwards G.

Instead, you need to load the whole bbold font. Here's a quick snippet to do that.

\documentclass{article}
\DeclareSymbolFont{bbold}{U}{bbold}{m}{n}
\DeclareSymbolFontAlphabet{\mathbbold}{bbold}

\begin{document}
$\mathbbold{a}$
\end{document}

bbold a

See also Blackboard bold characters

edited Apr 13 '17 at 12:34

Community

1

answered Jul 02 '14 at 14:00

Matthew Leingang

44,937
14
131
195

1

good sleuthing. i would never have gotten this without help. i'm much more accustomed to the shape shown in the unicode charts at U+1D552. – barbara beeton Jul 02 '14 at 14:23
@barbarabeeton: Thanks. It was a hunch and some quick googling. Knowing that it was used as a variable instead of a binary operation or relation was a hint that it might be a letter of some kind. – Matthew Leingang Jul 02 '14 at 14:37
@MatthewLeingang i can't get a a letter with good quality, if i run your code i get a a pixelled, very different to this test. If you can help me! – skpblack Jul 02 '14 at 14:47
@skpblack: Hm, it's possible your installation doesn't have the fonts at the size you want? What does the log file say? – Matthew Leingang Jul 02 '14 at 14:48
Something like `LaTeX Font Info: Try loading font information for U+bbold on input line 9.
("C:\Program Files\LaTeX\MiKTeX 2.9\tex\latex\jknappen\ubbold.fd" File: ubbold.fd 1996/01/01 Blackboard Bold Font Definition File (jk) ) [1`
– skpblack Jul 02 '14 at 14:55
@skpblack: Debugging font installations are not my expertise, so to get more exposure to your problem I think you should ask a separate question, linking back to this one. – Matthew Leingang Jul 02 '14 at 15:08
Simply, do you have the bold-type1 package. That might explain. – Bernard Jul 02 '14 at 15:10
@MatthewLeingang Thanks, i can solve my problem installing the bbm package. After of this i believe that a missed fonts were installed. I did not even include it in the preamble and your code works well. – skpblack Jul 02 '14 at 15:12
@skpblack: I think the fonts used by the bbm package are in the blackboard bold shape, but not the same as the bbold font. – Matthew Leingang Jul 02 '14 at 15:16

score 3 · Answer 2 · edited Jul 02 '14 at 14:59

I think Matthew is right, there is the pdffonts output from the article Barbara linked to

name                                 type              emb sub uni object ID
------------------------------------ ----------------- --- --- --- ---------
Times-Roman                          Type 1C           yes no  no     763  0
Times-Bold                           Type 1C           yes no  no     764  0
MTSYB                                Type 1C           yes no  yes    765  0
MTSYN                                Type 1C           yes no  yes    771  0
MarVoSym                             Type 1C           yes no  yes    778  0
Times-Italic                         Type 1C           yes no  no     459  0
MTMI                                 Type 1C           yes no  yes    463  0
BBOLD5                               Type 1C           yes no  yes    480  0
BBOLD7                               Type 1C           yes no  yes    475  0
MTEX                                 Type 1C           yes no  yes    470  0
Courier                              Type 1C           yes no  no     491  0
MSBM10                               Type 1C           yes no  yes    500  0

What symbol is this?

2 Answers2