considering the flowing code: ———————————————————————— from sage.symbolic.assumptions import GenericDeclaration; var('lamda,n,k,p'); decl1 = GenericDeclaration(k, 'integer'); decl1.assume(); assume(k>0,k>1,n>k,lamda>0,lamda<n); ep="binomial(n,k)<em">p^k(1-p)^(n-k); ep=ep.subs_expr(p==lamda/n); ep=ep.subs_expr(binomial(n,k)==factorial(n)/factorial(k)/factorial(n-k)); ep=limit(ep,n=oo); ep.simplify_full(); ———————————————————————— the result is: lamda^klimit((-(lamda - n)/n)^nfactorial(n)/((-lamda + n)^kfactorial(-k + n)), n, +Infinity)/factorial(k) ———————————————————————— it is not the simplest form. In fact , sage will give me the simplest form as below when I paste the result above to sage again. ———————————————————————— lamda^ke^(-lamda)/factorial(k) ———————————————————————— the question is how can i get the simplest form directly?