Rather than create an explicit 3-dimensional set that I must
manually populate, only to turn around and manually specify the same
set for each index in the eff parameter indices, is it possible to
harvest the information contained in the parameter indices? I might
use this to automatically generate the set of valid indices over
which, say, the usable life of each process might be:
param usable_life {(p,v) in valid_processes} default 30 :=
coal_pp 2015 15
coal_pp 2020 17 # GLPK would ostensibly provide an error
# message because the eff parameter does
# not have the <coal_pp, 2017> tuple in
# the (p,v) subset of it's indices.
;