Chasing Positive Difference
How a one-line lemma about truncated subtraction turned into a multi-week descent through the whole arithmetic of a natural numbers object — with a 1954 paper by Goodstein as the pivotal, but insufficient, key.
How a one-line lemma about truncated subtraction turned into a multi-week descent through the whole arithmetic of a natural numbers object — with a 1954 paper by Goodstein as the pivotal, but insufficient, key.