bv-sb-d1

Theorem.

Arguments:

y (st), x (sv), phi (pr), z (sv),

Dummy variables:

w (sv),

Distinct variable conditions:

(w, y), (w, x), (w, phi), (w, z), (z, y),

Hypotheses:

(z bound in phi)

Assertions:

(z bound in [y/x]phi)

Proof:

Hyp Ref Line Expr
Hypo1(z bound in phi)
ax10ex2(forallx(xeqz)to(existsx((xeqw)wedgephi)leftrightarrowexistsz((xeqw)wedgephi)))
bv-idvar3(z bound in forallx(xeqz))
bv-∃b4(z bound in existsz((xeqw)wedgephi))
2, 3, 4bvdefd5(forallx(xeqz)to(existsx((xeqw)wedgephi)toforallzexistsx((xeqw)wedgephi)))
ax166(forallz(zeqw)to((xeqw)toforallz(xeqw)))
ax127(lnotforallz(zeqx)to(lnotforallz(zeqw)to((xeqw)toforallz(xeqw))))
7com12i8(lnotforallz(zeqw)to(lnotforallz(zeqx)to((xeqw)toforallz(xeqw))))
6ax19(forallz(zeqw)to(lnotforallz(zeqx)to((xeqw)toforallz(xeqw))))
8, 9casei10(lnotforallz(zeqx)to((xeqw)toforallz(xeqw)))
10naleqcoms11(lnotforallx(xeqz)to((xeqw)toforallz(xeqw)))
fv-nalx12(x bound in lnotforallx(xeqz))
1df-Bvp13(phitoforallzphi)
13ax114(lnotforallx(xeqz)to(phitoforallzphi))
11, 14fv-and15(lnotforallx(xeqz)to(((xeqw)wedgephi)toforallz((xeqw)wedgephi)))
12, 15fv-exyd16(lnotforallx(xeqz)to(existsx((xeqw)wedgephi)toforallzexistsx((xeqw)wedgephi)))
5, 16casei17(existsx((xeqw)wedgephi)toforallzexistsx((xeqw)wedgephi))
17df-Bvp18(z bound in existsx((xeqw)wedgephi))
ax17-bv19(z bound in (weqy))
18, 19bv-∧20(z bound in ((weqy)wedgeexistsx((xeqw)wedgephi)))
20bv-∃21(z bound in existsw((weqy)wedgeexistsx((xeqw)wedgephi)))
df-sb22([y/x]phileftrightarrowexistsw((weqy)wedgeexistsx((xeqw)wedgephi)))
21, 22bvdef23(z bound in [y/x]phi)