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diff --git a/plugins/setoid_ring/Rings_Q.v b/plugins/setoid_ring/Rings_Q.v
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+++ b/plugins/setoid_ring/Rings_Q.v
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+Require Export Cring.
+Require Export Integral_domain.
+
+(* Rational numbers *)
+Require Import QArith.
+
+Instance Qops: (@Ring_ops Q 0%Q 1%Q Qplus Qmult Qminus Qopp Qeq).
+
+Instance Qri : (Ring (Ro:=Qops)).
+constructor.
+try apply Q_Setoid. 
+apply Qplus_comp. 
+apply Qmult_comp. 
+apply Qminus_comp. 
+apply Qopp_comp.
+ exact Qplus_0_l. exact Qplus_comm. apply Qplus_assoc.
+ exact Qmult_1_l.  exact Qmult_1_r. apply Qmult_assoc.
+ apply Qmult_plus_distr_l.  intros. apply Qmult_plus_distr_r. 
+reflexivity. exact Qplus_opp_r.
+Defined.
+
+Instance Qcri: (Cring (Rr:=Qri)).
+red. exact Qmult_comm. Defined.
+
+Lemma Q_one_zero: not (Qeq 1%Q 0%Q).
+unfold Qeq. simpl. auto with *. Qed.
+
+Instance Qdi : (Integral_domain (Rcr:=Qcri)). 
+constructor. 
+exact Qmult_integral. exact Q_one_zero. Defined.