What symbol is this?

Question

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

Answer 1

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

See also Blackboard bold characters

Answer 2

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