In mathematical practice not all results carry the same “weight”. Three different names are used depending on the role a result plays.

Remark — Lemma, theorem, corollary

  • A lemma is a “service” result, proved in order to be used in the proof of a more important theorem.
  • A theorem is the main result.
  • A corollary is an immediate consequence of an already proved theorem.

The lemmas prepare the theorem; from the theorem the corollaries follow immediately.

Topics: Euclidean geometry
Concepts: Corollary · Lemma · Theorem