Definition Qmult_resp_Qlt_pos_r:= Qlt_Qmult_cancel_r :  forall t x y : Q, Zero < t -> x * t < y * t -> x < y.Definition Qmult_resp_Qlt_pos_l:= Qlt_Qmult_cancel_l: forall t x y : Q, Zero < t -> t * x < t * y -> x < y.

(* Specifications: *)
Lemma Qmult_resp_Qlt_neg_r: forall t x y : Q, t < Zero -> x * t < y * t -> y < x.
Lemma Qmult_resp_Qlt_neg_l: forall t x y : Q, t < Zero -> t * x < t * y -> y < x.
Lemma Qeq_Qminus : forall x y, x=y -> x-y=Zero.
Lemma Qminus_Qeq : forall x y, x-y=Zero -> x=y.
Lemma Qlt_not_eq': forall x y : Q, x < y -> x <> y.
Lemma Qinv_neg: forall q : Q, q<Zero -> Qinv q< Zero.
Lemma Qle_Qopp_pos:forall q : Q, q<= Zero -> Zero<= Qopp q.
Lemma Qopp_Qone_Qlt_Qone: Qopp Qone < Qone.
Lemma Qle_mult_nonneg_pos: forall x y : Q, Zero <= x -> Zero < y -> Zero <= x * y.
Lemma Qle_mult_pos_nonneg: forall x y : Q, Zero<x -> Zero <= y -> Zero <= x * y.
Lemma Qle_mult_nonpos_neg: forall x y : Q, x<=Zero -> y<Zero -> Zero <= x * y.
Lemma Qle_mult_neg_nonpos: forall x y : Q, x<Zero -> y<=Zero -> Zero <= x * y.
Lemma Qle_Qdiv_nonpos_pos: forall x y : Q, x <= Zero -> Zero < y -> x / y <= Zero.
Lemma Qle_Qdiv_nonneg_neg: forall x y : Q, Zero <= x -> y < Zero -> x / y <= Zero.
Lemma Qle_Qdiv_nonneg_pos: forall x y : Q, Zero<=x -> Zero < y -> Zero<=x / y.
Lemma Qle_Qdiv_nonpos_neg: forall x y : Q, x<=Zero -> y<Zero -> Zero<=x / y.
Lemma Qlt_mult_neg_neg: forall x y : Q, x<Zero-> y<Zero -> Zero < x * y.
Lemma Qmult_reg_l: forall x y z: Q, z <> Zero -> z*x = z*y -> x=y.
Lemma Qmult_reg_r: forall x y z: Q, z <> Zero -> x*z = y*z -> x=y.
Lemma Qmult_Qdiv: forall x y z t : Q, z <> Zero -> t <> Zero -> x * t = y * z -> x / z = y / t.
Lemma Qdiv_Qmult: forall x y z t : Q, z <> Zero -> t <> Zero -> x / z = y / t -> x * t = y * z.
Lemma Qdiv_Qdiv_Qmult_numerator: forall x y z, y<>Zero -> z<>Zero ->(x/y)/z = x/(y*z).
Lemma Qdiv_Qdiv_Qmult_denominator: forall x y z, y<>Zero -> z<>Zero -> x/(y/z) = (x*z)/y.
Lemma Qdiv_Qplus_Qmult: forall x y z, y<>Zero -> x/y + z = (x+y*z)/y.
Lemma Qdiv_Qminus_Qmult: forall x y z, y<>Zero -> x/y - z = (x-y*z)/y.
Lemma Qminus_Qdiv_Qmult: forall x y z, ~(y=Zero)->z-x/y=(y*z-x)/y.
Lemma Qplus_Qdiv_Qmult: forall x y z, ~(y=Zero)->z+x/y=(y*z+x)/y.
Lemma Qle_reg_mult_r: forall x y z : Q, Zero < x -> y <=z -> y * x <=z * x.
Lemma Qle_reg_mult_l: forall x y z : Q, Zero < x -> y <= z -> x * y <= x * z.
Lemma Qmult_resp_Qle_pos_r: forall t x y : Q, Zero < t -> x * t <= y * t -> x <= y.
Lemma Qmult_resp_Qle_pos_l: forall t x y : Q, Zero < t -> t * x <= t * y -> x <= y.
Lemma Qmult_resp_Qle_neg_r: forall t x y : Q, t < Zero -> x * t <= y * t -> y <= x.
Lemma Qmult_resp_Qle_neg_l: forall t x y : Q, t < Zero -> t * x <= t * y -> y <= x.
Lemma Qmult_Qdiv_pos_Qle: forall x y z t : Q, Zero < z -> Zero < t -> x * t <= y * z -> x / z <= y / t.
Lemma Qmult_Qle_compat: forall n m p q : Q, n <= p -> m <= q -> Zero <= n -> Zero <= m -> n * m <= p * q.
Lemma Qdiv_num_denom_explicit: forall q1 q2 p : Q, q2 <> Zero -> p <> Zero -> q1 / q2 = (q1 * p)/ (q2 * p).
Lemma Qle_opp: forall x y : Q, - x <= - y -> y <= x.
Lemma Qmult_pos_Qle_Qdiv: forall x y z : Q, Zero<z -> x * z<=y -> x <= y / z.
Lemma Qmult_neg_Qle_Qdiv: forall x y z : Q, z <Zero -> y <= x * z -> x <= y / z.
Lemma Qmult_pos_Qdiv_Qle: forall x y z : Q, Zero<z -> y<=x*z -> y/z <= x.
Lemma Qmult_neg_Qdiv_Qle: forall x y z : Q, z <Zero -> x*z<=y -> y/z<=x.
Lemma Qmult_pos_Qlt_Qdiv: forall x y z : Q, Zero<z -> x * z<y -> x < y/z.
Lemma Qmult_neg_Qlt_Qdiv: forall x y z : Q, z <Zero -> y < x * z -> x < y / z.
Lemma Qmult_pos_Qdiv_Qlt: forall x y z : Q, Zero<z -> y<x*z -> y/z < x.
Lemma Qmult_neg_Qdiv_Qlt: forall x y z : Q, z <Zero -> x*z<y -> y/z<x.
Lemma Qmult_Qdiv_pos_neg_Qle:forall x y z t : Q, Zero < z -> t<Zero -> y * z <= x * t -> x / z <= y / t.
Lemma Qmult_Qdiv_neg_pos_Qle:forall x y z t : Q, z<Zero -> Zero<t -> y * z <= x * t -> x / z <= y / t.
Lemma Qmult_Qdiv_neg_Qle:forall x y z t : Q, z<Zero -> t<Zero -> x * t<=y * z -> x / z <= y / t.
Lemma Qopp_involutive: forall q, Qopp (Qopp q) = q.
Lemma Qopp_Qle: forall x y, y <= x -> - x <= - y.
Lemma Qopp_Qlt: forall x y, y < x -> - x < - y.
Lemma Qle_reg_mult_r_strong: forall x y z : Q, Zero <= x -> y <= z -> y * x <= z * x.
Lemma Qle_reg_mult_l_strong: forall x y z : Q, Zero <= x -> y <= z -> x * y <= x * z.
Lemma Qlt_Qdiv_denom_neg_neg: forall x y:Q, y<Zero -> x / y < Zero -> Zero < x.
Lemma Qlt_Qdiv_denom_neg_pos: forall x y:Q, y<Zero -> Zero< x / y -> x<Zero.
Lemma Qlt_Qdiv_denom_pos_neg: forall x y:Q, Zero<y -> x / y < Zero -> x<Zero.
Lemma Qlt_Qdiv_denom_pos_pos: forall x y:Q, Zero<y -> Zero< x / y -> Zero<x.
Lemma Qle_Qdiv_denom_neg_nonpos: forall x y:Q, y<Zero -> x / y <= Zero -> Zero <= x.
Lemma Qle_Qdiv_denom_neg_nonneg: forall x y:Q, y<Zero -> Zero<= x / y -> x<=Zero.
Lemma Qle_Qdiv_denom_pos_nonpos: forall x y:Q, Zero<y -> x / y <= Zero -> x<=Zero.
Lemma Qle_Qdiv_denom_pos_nonneg: forall x y:Q, Zero<y -> Zero<= x / y -> Zero<=x.
Lemma Qlt_neg_Qopp: forall x : Q, - x < Zero->Zero < x.
Lemma Qlt_pos_Qopp: forall x : Q, Zero < - x->x<Zero.
Lemma Qmult_mult_Qle_Qone_Qopp_Qone: forall q, -Qone<=q -> q<= Qone -> q*q <= Qone.
Lemma Qinv_resp_nonzero_Qdiv:forall q, q <> Zero -> (Qone/q)<>Zero.
Lemma Qmult_Qlt_Qle_nonneg_pos_compat: forall n m p q, n < p -> m <= q -> Zero <= n -> Zero < q -> n * m < p * q.
Lemma Qmult_Qlt_Qle_pos_nonneg_compat: forall n m p q, n <= p -> m < q -> Zero < p -> Zero <= m -> n * m < p * q.