What does this symbol mean (white circle connected with black bullet; both are linked by a horizontal line) and how can I write it in LaTeX?

Question

The symbol appears within the definition of the Fourier transform. The German text translates as follows:

The Fourier transform of a continuous, integrable function $s(t)$ is given as

Math stuff with ominous symbol.

The equivalence $e^{ix} = \cos(x) + j\sin(x)$ is called Euler’s formula.

Answer 1

To write it in LATEX you need to include the package "txfonts" and use $\multimapdotbothA$.

Answer 2

I don't think it means anything distinctly mathematical. I think it is read "is defined by".

Try detexify.