Such silly errors are entirely excusable. I would like to know more about all these commenters who are so up in arms about this mistake that they did not deign to complete the article. You would have been very unhappy people before English spelling was standardized. I cannot imaging rejecting the substance of an article due to such cosmetic issues. I guess this is a consequence of the group here considering your postings on HN to be some kind of resume or CV. Colour me unimpressed with the herd.