ضمان in English:

I can guarantee that you won’t regret it.

There was no guarantee of a contract at the end of the internship.

under guarantee

Should the word processor go wrong, we guarantee to replace it free of charge.

There is a good number of problems for which the Karush-Kuhn-Tucker conditions are insufficient to guarantee optimality, but this doesn't change the fact that these conditions are an indispensable tool for doing optimization.

What guarantee do I have that you'll keep up your end of the bargain?

A firewall will guarantee Internet security.

However, the guarantee is not effective at all outside the fixed form.

This is genuine Kutani-ware. I guarantee it.

We will grant you a special discount of 5% provided that you could guarantee placing regular orders.

Relying on strength alone cannot guarantee victory.

I guarantee you will get a good score if you study a lot!

"On the other hand this is a guarantee of stable income for our farmers. "

Their savings will guarantee a nice retirement for them.

They are guaranteed to arrive in style and always in plenty of time for that important day.