Understanding Symbolic Logic, Virginia Klenk, 5th ed., Pearson Prentice Hall, 2008, Unit 18, Ex. 2b, p. 354

 Prove the logical truth.

1.     (∃x)(y)(z)Fxyz 2.     (y)(z)Fmyz 3.     (z)Fmyz 4.     Fmyz 5.     (∃x)Fmyz 6.     (y)(∃x)Fxyz 7.     (z)(y)(∃x)Fxyz 8.     (y)(z)(∃x)Fxyz 9.     (∃x)(y)(z)Fxyz ⊃ (y)(z)(∃x)Fxyz

/(∃x)(y)(z)Fxyz ⊃ (y)(z)(∃x)Fxyz ACP 1 EI 2 UI 3 UI 4 EG 5 UG 6 UG Equiv (Com) 1-8 CP