matita/matita/contribs/lambdadelta/ground_2/xoa_props.ma

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  14
  15 include "basics/logic.ma".
  16 include "ground_2/xoa_notation.ma".
  17 include "ground_2/xoa.ma".
  18
  19 interpretation "logical false" 'false = False.
  20
  21 interpretation "logical true" 'true = True.
  22
  23 lemma ex2_1_comm: ∀A0. ∀P0,P1:A0→Prop. (∃∃x0. P0 x0 & P1 x0) → ∃∃x0. P1 x0 & P0 x0.
  24 #A0 #P0 #P1 * /2 width=3/
  25 qed.