r first economic papers, perhaps you are confused about function 
% notation. Economic models include potentially a lot of variables, and different 
% notations are used based on personal preference. Make sure you use consistent 
% notations, and state clearly what your notations mean.
% 
% In general, the letter $f$ represents a particular rule of mapping, if there 
% are multiple functional relationships in an economic model, different letters 
% could be used, for example:
% 
% $$y = Y(h), l = L(h), u = 