This is a quality discussion. I'm British and lecture on optimization at a major UK university where I have crossed swords occasionally with colleagues and students who insist on change my -ize to -ise. Unfortunately I can't see the preferred usage becoming universal since it would mean asking academics in other groups not to use -ise. UK engineers seem to be the worst when it comes to using -ise, and you can draw your own conclusions regarding their insularity! I appreciate the link in the previous post, too.