<i>Mochizuki would have benefited greatly from such a co-author, in order to truly prove his result to the community.</i><p>Except that, from reading the article, it sounds like he doesn&#x27;t much care about proving his result to the community. Don&#x27;t make the mistake of assigning the motives and values of a founder to a late-career tenured mathematician. According to the article, he doesn&#x27;t care for travel. It&#x27;s not a stretch to conclude that he doesn&#x27;t care to communicate his proof to other mathematicians.<p>I&#x27;m guessing he found an argument that was sufficient to convince him (and only him), put it online as a slight concession to his colleagues, and then kicked his feet back.<p>Surely <i>everyone else</i> would benefit from his having a co-author, but it sounds like he can&#x27;t be bothered, and doesn&#x27;t care if no one else understands his ideas.