I was reading Serge Lang’s “Algebra”, the revised third edition. In p. 53, Lang introduces a concept of a category with a special cursive which I’ve never seen before. It is shown above. For me, it looks like some kind of alphabet ‘a’.
I first thought that it was \mathscr or \mathcal, but I couldn’t find such an alphabet in the $\LaTeX$ font table. Does anyone know what it is?