| Description: Deduction introducing an
embedded antecedent.
Naming convention: We often call a theorem a
"deduction" and suffix
its label with "d" whenever the hypotheses and conclusion are
each
prefixed with the same antecedent. This allows us to use the theorem in
places where (in traditional textbook formalizations) the standard
Deduction Theorem would be used; here would be replaced with a
conjunction (df-an 198) of the hypotheses of the would-be deduction.
By
contrast, we tend to call the simpler version with no common antecedent
an "inference" and suffix its label with "i";
compare theorem a1i 7.
Finally, a "theorem" would be the form with no hypotheses; in
this case
the "theorem" form would be the original axiom ax-1 3. In
propositional
calculus we usually prove the theorem form first without a suffix on its
label (e.g. pm2.43 57 vs. pm2.43i 58 vs. pm2.43d 59), but (much) later
we often suffix the theorem form's label with "t" as in negnegt 4157 vs.
negneg 4154, especially when our "weak deduction
theorem" dedth 1784 is used
to prove the theorem form from its inference form. When an inference is
converted to a theorem by eliminating an "is a set"
hypothesis, we
sometimes suffix the theorem form with "g" (for somewhat
misnamed
"generalized") as in uniex 1947 vs. uniexg 1948. |