Dear all,

Im new in GAMS, and setting up a model for the production of ethanol (etoh) in biorefineries. I have some questions I not yet found out about. Can anyone help me? here we go:

Question 1. I have 4 sets j, k, g, t (resp. products, technologies, grids, and time) . one formula is P(j,k,g,t) that is a certain production of type j of techn k, in grid g, for time t. Production type j consists of etoh, electricity, and DDGS. I want to define a formula specific for one product, etoh, for example: P(“etoh”, k,g,t) =g= 0. How should I formulate that in my GAMS? If I do it like the example between quotes, it gives the error “185 Set identifier or ‘*’ expected”.

or another example

278 xP(“etoh”,k,g,t)… P(“etoh”,k,g,t) =e= sum(i, Pf(i,k,g,t))

**** $150 $148$653 $8,409

with errors

150 Symbolic equations redefined

148: Dimension different - The symbol is referenced with more/less indices as declared

135: Incompatible operands for relational operator

653 The left side of an equation cannot be a set expression

8 : ‘)’ expected

another example:

248 cddgs1(“ddgs”,k,g,t)… P(“ddgs”,k,g,t) =e= 0 (ddgs is a product type, an identifier within the set ‘j’)

**** $148$653$409

148: Dimension different - The symbol is referenced with more/less indices as declared

653 The left side of an equation cannot be a set expression

another example:

258 xcetoh1(“etoh”,k,g,t)… P(“etoh”,k,g,t) =l= sum(p, Ã¾(p,k,g,t) * 3 * ER(p))

**** $140 $148$653 $119,148,8,654,409

140 Unknown symbol

148: Dimension different - The symbol is referenced with more/less indices as declared

653 The left side of an equation cannot be a set expression

etc etc

I will post the other questions in another mail

Thank you all very much in advance for helping me

greetings,

bendjy

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