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Syntax Definition ciun 4353
Description: Extend class notation to include indexed union. Note: Historically (prior to 21-Oct-2005), set.mm used the notation 𝑥𝐴𝐵, with the same union symbol as cuni 4270. While that syntax was unambiguous, it did not allow for LALR parsing of the syntax constructions in set.mm. The new syntax uses a distinguished symbol instead of and does allow LALR parsing. Thanks to Peter Backes for suggesting this change.
Hypotheses
Ref Expression
vx setvar 𝑥
cA class 𝐴
cB class 𝐵
Assertion
Ref Expression
ciun class 𝑥𝐴 𝐵

See definition df-iun 4355 for more information.

Colors of variables: wff setvar class
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