matita/matita/lib/lambda-delta/xoa_props.ma

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  14
  15 include "lambda-delta/xoa_notation.ma".
  16 include "lambda-delta/xoa_defs.ma".
  17
  18 lemma ex2_1_comm: ∀A0. ∀P0,P1:A0→Prop. (∃∃x0. P0 x0 & P1 x0) → ∃∃x0. P1 x0 & P0 x0.
  19 #A0 #P0 #P1 * /2/
  20 qed.