Hello, I am a new to MINLP and try to solve a simple problem. However, it turns out not that simple. 
Below is my code. It doesnot work. Could anyone let me know I should change the formulation so I can make it work? (It will very much appreciated if you could provide an example) Thank you very much for your help.
set k/k1k2/
n/p1p4/
;
Parameter p(n) ‘price’ / p1 50
p2 60
p3 70
p4 70/;
Variable pri_dif
price(n,k)
mean(k)
sum_price(k)
;
binary variable m(n,k)
;
Equations
Obj_cluster objective for clustering
assign_limit
kluster_mean
;
Obj_cluster…
pri_dif =E= sum((n,k),(abs(p(n)$m(n,k)- mean(k)$m(n,k)))**2)
;
kluster_mean(k)…
mean(k) =e= sum(n,p(n)$m(n,k))/sum(n,m(n,k));
;
assign_limit(n)…
sum(k,m(n,k))=e= 1
;
Model edc / all /
solve edc using minlp minimizing pri_dif;