Rule of Theorem Introduction

Definition
We may introduce, at any stage of a proof (citing TI), a theorem already proved, or a substitution instance of such a theorem, together with a reference to the theorem that is being cited.

Proof
This theorem is a corollary of the Rule of Sequent Introduction.

Application
Using this rule, we can use theorems that we have derived in order to shorten proofs which may otherwise be long and unwieldy.

Technical Note
When invoking Rule of Theorem Introduction in a tableau proof, use the TheoremIntro template:



where:
 * is the number of the line on the tableau proof where the Rule of Theorem Introduction is to be invoked
 * is the statement of logic that is to be displayed in the Formula column, without the  delimiters
 * is the link to the theorem in question that will be displayed in the Notes column.