I have these two definitions:
\documentclass[12pt]{article} \usepackage{amsmath} \begin{document} \begin{flalign*} &\boldsymbol{R*^\sigma} & \sigma_{superset}(F)&=\sigma_{superset}(F')&\\ &\boldsymbol{R*_{weak}^\sigma} & \sigma_{superset}(F)&=\sigma_{superset}(F')\cap\mathcal{P}(A)& \end{flalign*} \end{document} Compiled, it looks like this: 
I want the equations to be aligned by "=" as they are; but also that they are not centered but quite next to the bold symbols. Like, also aligned left.
It should look like this (done with MS Paint): 
1 Answer
If you don't mind that all equations will be left aligned, you could use the fleqn option of amsmath:
\documentclass[12pt]{article} \usepackage[fleqn]{amsmath} \setlength{\mathindent}{0pt} \begin{document} \noindent text \begin{alignat*}{3} &\boldsymbol{R*^\sigma} & \sigma_{superset}(F)&=\sigma_{superset}(F')\\ &\boldsymbol{R*_{weak}^\sigma} \quad& \sigma_{superset}(F)&=\sigma_{superset}(F')\cap\mathcal{P}(A) \end{alignat*} \end{document} If you like to keep other equations centred, you could also switch temporarily:
\documentclass[12pt]{article} \usepackage{amsmath} \begin{document} \[ a \] { \makeatletter \@fleqntrue \makeatother \begin{alignat*}{4} &\boldsymbol{R*^\sigma} & \sigma_{superset}(F)&=\sigma_{superset}(F')\\ &\boldsymbol{R*_{weak}^\sigma} \quad& \sigma_{superset}(F)&=\sigma_{superset}(F')\cap\mathcal{P}(A) \end{alignat*} } \[ a \] \end{document} 
