About Kronecker's delta symbol under a summation sign

Dear List,

I apologize in advance for a potentially naive question, but I was not
able to find an answer by myself from the documentation and / or from
previous posts. So here it is:

When I type:

(%i5) sum(kron_delta(i,j),i, 1,N);

I would like to get the answer:

(%o5) 1

It is assumed here that N is an integer >= 1 and that j is also an
integer with 1 <= j <= N. I've tried to make Maxima "aware" of my
assumptions with:

(%i1) declare(N,integer)$
(%i2) assume(N >= 1)$
(%i3) declare(j, integer)$
(%i4) assume(j >= 1 and j <= N)$

But that does not seem to be enough...
Of course,

(%i6) sum(kron_delta(i,j),i,1,N), N=10, j=5;

works.

Thanks in advance for your time and help,

Christophe
--
A Master Carpenter has many tools and is expert with most of them. If
you only know how to use a hammer, every problem starts to look like a
nail.
Stay away from that trap.
Richard B Johnson.
--

Christophe Pouzat
Laboratoire de Physiologie Cerebrale
CNRS UMR 8118
UFR biomedicale de l'Universite Paris-Descartes
45, rue des Saints Peres
75006 PARIS
France

tel: +33 (0)1 42 86 38 28
fax: +33 (0)1 42 86 38 30
mobile: +33 (0)6 62 94 10 34
web: http://www.biomedicale.univ-paris5.fr/physcerv/C_Pouzat.html
sip:christophe.pouzat at ekiga.net