Metamath Proof Explorer

Theorem pm2.43d

Description: Deduction absorbing redundant antecedent. Deduction associated with pm2.43 and pm2.43i . (Contributed by NM, 18-Aug-1993) (Proof shortened by Mel L. O'Cat, 28-Nov-2008)

Ref Expression
Hypothesis pm2.43d.1 φ ψ ψ χ
Assertion pm2.43d φ ψ χ


Step Hyp Ref Expression
1 pm2.43d.1 φ ψ ψ χ
2 id ψ ψ
3 2 1 mpdi φ ψ χ