Metamath Proof Explorer


Theorem addsunif

Description: Uniformity theorem for surreal addition. This theorem states that we can use any cuts that define A and B in the definition of surreal addition. Theorem 3.2 of Gonshor p. 15. (Contributed by Scott Fenton, 21-Jan-2025)

Ref Expression
Hypotheses addsunif.1 φ L s R
addsunif.2 φ M s S
addsunif.3 φ A = L | s R
addsunif.4 φ B = M | s S
Assertion addsunif φ A + s B = y | l L y = l + s B z | m M z = A + s m | s w | r R w = r + s B t | s S t = A + s s

Proof

Step Hyp Ref Expression
1 addsunif.1 φ L s R
2 addsunif.2 φ M s S
3 addsunif.3 φ A = L | s R
4 addsunif.4 φ B = M | s S
5 1 2 3 4 addsuniflem φ A + s B = a | b L a = b + s B c | d M c = A + s d | s e | f R e = f + s B g | h S g = A + s h
6 oveq1 l = b l + s B = b + s B
7 6 eqeq2d l = b y = l + s B y = b + s B
8 7 cbvrexvw l L y = l + s B b L y = b + s B
9 eqeq1 y = a y = b + s B a = b + s B
10 9 rexbidv y = a b L y = b + s B b L a = b + s B
11 8 10 bitrid y = a l L y = l + s B b L a = b + s B
12 11 cbvabv y | l L y = l + s B = a | b L a = b + s B
13 oveq2 m = d A + s m = A + s d
14 13 eqeq2d m = d z = A + s m z = A + s d
15 14 cbvrexvw m M z = A + s m d M z = A + s d
16 eqeq1 z = c z = A + s d c = A + s d
17 16 rexbidv z = c d M z = A + s d d M c = A + s d
18 15 17 bitrid z = c m M z = A + s m d M c = A + s d
19 18 cbvabv z | m M z = A + s m = c | d M c = A + s d
20 12 19 uneq12i y | l L y = l + s B z | m M z = A + s m = a | b L a = b + s B c | d M c = A + s d
21 oveq1 r = f r + s B = f + s B
22 21 eqeq2d r = f w = r + s B w = f + s B
23 22 cbvrexvw r R w = r + s B f R w = f + s B
24 eqeq1 w = e w = f + s B e = f + s B
25 24 rexbidv w = e f R w = f + s B f R e = f + s B
26 23 25 bitrid w = e r R w = r + s B f R e = f + s B
27 26 cbvabv w | r R w = r + s B = e | f R e = f + s B
28 oveq2 s = h A + s s = A + s h
29 28 eqeq2d s = h t = A + s s t = A + s h
30 29 cbvrexvw s S t = A + s s h S t = A + s h
31 eqeq1 t = g t = A + s h g = A + s h
32 31 rexbidv t = g h S t = A + s h h S g = A + s h
33 30 32 bitrid t = g s S t = A + s s h S g = A + s h
34 33 cbvabv t | s S t = A + s s = g | h S g = A + s h
35 27 34 uneq12i w | r R w = r + s B t | s S t = A + s s = e | f R e = f + s B g | h S g = A + s h
36 20 35 oveq12i y | l L y = l + s B z | m M z = A + s m | s w | r R w = r + s B t | s S t = A + s s = a | b L a = b + s B c | d M c = A + s d | s e | f R e = f + s B g | h S g = A + s h
37 5 36 eqtr4di φ A + s B = y | l L y = l + s B z | m M z = A + s m | s w | r R w = r + s B t | s S t = A + s s