I recently came across the following result attributed to Gurevich, according to which I understood that the class of problems solvable by primitive recursive functions is precisely the class L of problems computable in logarithmic space.
I attach a screenshot from Neil Immerman's book Descriptive Complexity, where I found the result.
Now, this seems very confusing to me, since it is known that the class PR is strictly bigger than L (see, for example, https://en.wikipedia.org/wiki/PR_(complexity) or https://math.stackexchange.com/questions/4170046/are-primitive-recursive-functions-computable-in-logarithmic-space). I imagine the theorem I attach is not talking about PR and L, but about something else. I'd appreciate some help in clarifying this.