Then Scholze got to Corollary
3.12 in the third paper.
Mathematicians usually use
the word “corollary” to denote
a theorem that is a secondary
consequence of a previous,
more important theorem.
But in the case of Mochizuki’s
Corollary 3.12, mathematicians agree
that it is at the core of the proof of abc.
Without it,
“there is no proof at all,”Calegari wrote.
“It is a critical step