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	Small improvements
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		@@ -139,35 +139,29 @@ Section properties.
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  Context {B : Type}.
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  Lemma isIn_singleproduct : forall (a : A) (b : B) (c : A) (Y : FSet B),
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  Lemma isIn_singleproduct (a : A) (b : B) (c : A) : forall (Y : FSet B),
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      isIn (a, b) (single_product c Y) = land (BuildhProp (Trunc (-1) (a = c))) (isIn b Y).
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  Proof.
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    intros a b c.
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    hinduction ; try (intros ; apply path_ishprop).
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    - apply path_hprop. symmetry. apply prod_empty_r.
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    - apply path_hprop ; symmetry ; apply prod_empty_r.
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    - intros d.
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      apply path_iff_hprop.
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      * intros. 
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         strip_truncations.
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         split ; apply tr ; try (apply (ap fst X)) ; try (apply (ap snd X)).
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        strip_truncations.
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        split ; apply tr ; try (apply (ap fst X)) ; try (apply (ap snd X)).
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      * intros [Z1 Z2].
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         strip_truncations.
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         rewrite Z1, Z2.
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         apply (tr idpath).
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        strip_truncations.
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        rewrite Z1, Z2.
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        apply (tr idpath).
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    - intros X1 X2 HX1 HX2.
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      unfold lor.
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      apply path_iff_hprop.
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      *  intros X.
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         strip_truncations.
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         destruct X as [H1 | H1].
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         ** rewrite HX1 in H1.
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            destruct H1 as [H1 H2].
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            split.
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         destruct X as [H1 | H1] ; rewrite ?HX1, ?HX2 in H1 ; destruct H1 as [H1 H2].
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         ** split.
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            *** apply H1.
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            *** apply (tr(inl H2)).
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         ** rewrite HX2 in H1.
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            destruct H1 as [H1 H2].
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            split.
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         ** split.
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            *** apply H1.
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            *** apply (tr(inr H2)).
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      * intros [H1 H2].
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@@ -176,15 +170,14 @@ Section properties.
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        rewrite HX1, HX2.
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        destruct H2 as [Hb1 | Hb2].
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        ** left.
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           split ;  try (apply (tr H1)) ; try (apply Hb1).
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           split ; try (apply (tr H1)) ; try (apply Hb1).
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        ** right.
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           split ; try (apply (tr H1)) ; try (apply Hb2).
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  Defined.
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  Definition isIn_product : forall (a : A) (b : B) (X : FSet A) (Y : FSet B),
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  Definition isIn_product (a : A) (b : B) (X : FSet A) (Y : FSet B) :
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      isIn (a,b) (product X Y) = land (isIn a X) (isIn b Y).
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  Proof.
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    intros a b X Y.
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    hinduction X ; try (intros ; apply path_ishprop).
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    - apply path_hprop ; symmetry ; apply prod_empty_l.
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    - intros.
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@@ -194,18 +187,14 @@ Section properties.
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      apply path_iff_hprop.
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      * intros X.
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        strip_truncations.
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        destruct X as [[H3 H4] | [H3 H4]].
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        ** split.
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           *** apply (tr(inl H3)).
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           *** apply H4.
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        ** split.
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           *** apply (tr(inr H3)).
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           *** apply H4.
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        destruct X as [[H3 H4] | [H3 H4]] ; split ; try (apply H4).
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        ** apply (tr(inl H3)).
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        ** apply (tr(inr H3)).
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      * intros [H1 H2].
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        strip_truncations.
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        destruct H1 as [H1 | H1].
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        ** apply tr ; left ; split ; assumption.
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        ** apply tr ; right ; split ; assumption.
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        destruct H1 as [H1 | H1] ; apply tr.
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        ** left ; split ; assumption.
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        ** right ; split ; assumption.
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  Defined.
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  (* The proof can be simplified using extensionality *)
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