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SUPPLEMENTARY MATERIAL (USERS' MATHBOXES)
Mathbox for Richard Penner
Set Theory and Ordinal Numbers
oaomoecl
Metamath Proof Explorer
Description: The operations of addition, multiplication, and exponentiation are closed.
Remark 2.8 of Schloeder p. 5. See oacl , omcl , oecl .
(Contributed by RP , 18-Jan-2025)
Ref
Expression
Assertion
oaomoecl
|- ( ( A e. On /\ B e. On ) -> ( ( A +o B ) e. On /\ ( A .o B ) e. On /\ ( A ^o B ) e. On ) )
Proof
Step
Hyp
Ref
Expression
1
oacl
|- ( ( A e. On /\ B e. On ) -> ( A +o B ) e. On )
2
omcl
|- ( ( A e. On /\ B e. On ) -> ( A .o B ) e. On )
3
oecl
|- ( ( A e. On /\ B e. On ) -> ( A ^o B ) e. On )
4
1 2 3
3jca
|- ( ( A e. On /\ B e. On ) -> ( ( A +o B ) e. On /\ ( A .o B ) e. On /\ ( A ^o B ) e. On ) )