I recall learning a "combinatorial" method for computing fundamental group of simplicial complexes (not graphs) involving maximal tree.
It is something like this: a group is generated by generators $g_{ab}$, where $ab$ is a 1-simplex of the simplicial complex $K$ not in the maximal tree $A$, subject to certain relations.
However I forget some details and would like to consult a reference. Is there any reference containing information on the above?