Hello everyone I had mistakes in my mod, which I already corrected due to communication with my prof. but I still have two issues:

Once it says that the tern I is already defined, because I have “var I” , but also “param I”. Can I just change the var into another Letter?

And the other issue is that I get this error: syntax error

context: minimize Kosten: sum{a in t} >>> s*x[a]+h*I[ <<< a]; #Minimierung der Gesamtkosten

Also the term x in my sum command is marked blue. What does it mean?

Here is my whole mod:

param T; #Anzahl der Perioden

param I; #Anfangsbestand

param s; #Rüstkostensatz

param h; #Lagerhaltungskosten

param M; #Eine “hinreichend große Zahl”

set t:=1…T; #Anzahl der Perioden

param d{t}; #Nachfrage der Periode

var q{t}; #Produktionsmenge in Periode t=1…T

var x{t} binary; #Entweder 1 bei Rüstung, sonst 0

var I{t}>=0; #Lagerbestand am Ende der Periode t=1…T

minimize Kosten: sum{a in t} s*x[a]+h*I[a]; #Minimierung der Gesamtkosten

subject to Lagerbestand{a in t}:I[a-1]+q[a]-d[a]=I[a];

subject to Produktionsmenge {a in t}:q[a]<=M*x[t];

subject to Produktionsmenge {a in t}:q[a]>=0;

subject to Lagerbestand {a in t}: I[a]>=0;

Need help asap.

Thanks in advance.

Anwar