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Step * 2 of Lemma strong-subtype-union-base


1. A : Type
2. strong-subtype(A;A ⋃ Base)
⊢ strong-subtype(A;Base ⋃ A)
BY
{ (UseTrans ⌜A ⋃ Base⌝⋅
   THEN Auto
   THEN BLemma `strong-subtype-ext-equal`
   THEN Auto
   THEN BLemma `subtype_rel_b-union_iff`
   THEN Auto) }

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Latex:

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Latex:

1.  A  :  Type
2.  strong-subtype(A;A  \mcup{}  Base)
\mvdash{}  strong-subtype(A;Base  \mcup{}  A)


By

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Latex:
(UseTrans  \mkleeneopen{}A  \mcup{}  Base\mkleeneclose{}\mcdot{}
  THEN  Auto
  THEN  BLemma  `strong-subtype-ext-equal`
  THEN  Auto
  THEN  BLemma  `subtype\_rel\_b-union\_iff`
  THEN  Auto)

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