Theorem drsb1 1177

Description: Formula-building lemma for use with the Distinctor Reduction Theorem. Part of Theorem 9.4 of [Megill] p. 448 (p. 16 of preprint).

Assertion

Ref	Expression
drsb1	|- (A.x x = y -> ([z / x]ph <-> [z / y]ph))

Proof of Theorem drsb1

Step	Hyp	Ref	Expression
1		equequ1 1136	. . . . 5 |- (x = y -> (x = z <-> y = z))
2	1	a4s 986	. . . 4 |- (A.x x = y -> (x = z <-> y = z))
3	2	imbi1d 615	. . 3 |- (A.x x = y -> ((x = z -> ph) <-> (y = z -> ph)))
4	2	anbi1d 619	. . . 4 |- (A.x x = y -> ((x = z /\ ph) <-> (y = z /\ ph)))
5	4	drex1 1158	. . 3 |- (A.x x = y -> (E.x(x = z /\ ph) <-> E.y(y = z /\ ph)))
6	3, 5	anbi12d 630	. 2 |- (A.x x = y -> (((x = z -> ph) /\ E.x(x = z /\ ph)) <-> ((y = z -> ph) /\ E.y(y = z /\ ph))))
7		df-sb 1174	. 2 |- ([z / x]ph <-> ((x = z -> ph) /\ E.x(x = z /\ ph)))
8		df-sb 1174	. 2 |- ([z / y]ph <-> ((y = z -> ph) /\ E.y(y = z /\ ph)))
9	6, 7, 8	3bitr4g 557	1 |- (A.x x = y -> ([z / x]ph <-> [z / y]ph))

Syntax hints:   -> wi 3   <-> wb 146   /\ wa 223  A.wal 956   = wceq 958  E.wex 982  [wsbc 1172

This theorem is referenced by:  sbequi 1230  sbco3 1259  sbcom 1260  sb9i 1265

This theorem was proved from axioms:  ax-1 4  ax-2 5  ax-3 6  ax-mp 7  ax-7 964  ax-gen 965  ax-8 966  ax-10 968  ax-12 970  ax-4 975  ax-5o 977  ax-6o 980  ax-9o 1125  ax-10o 1142

This theorem depends on definitions:  df-bi 147  df-an 225  df-ex 983  df-sb 1174

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