Metamath Proof Explorer

Theorem 2a1dd

Description: Double deduction introducing two antecedents. Two applications of 2a1dd . Deduction associated with 2a1d . Double deduction associated with 2a1 and 2a1i . (Contributed by Jeff Hankins, 5-Aug-2009)

Ref Expression
Hypothesis 2a1dd.1 φ ψ χ
Assertion 2a1dd φ ψ θ τ χ


Step Hyp Ref Expression
1 2a1dd.1 φ ψ χ
2 1 a1dd φ ψ τ χ
3 2 a1dd φ ψ θ τ χ