# Library Coq.ZArith.Zorder

Binary Integers : results about order predicates Initial author : Pierre CrÃ©gut (CNET, Lannion, France)
THIS FILE IS DEPRECATED. It is now almost entirely made of compatibility formulations for results already present in BinInt.Z.

Require Import BinPos BinInt Decidable Zcompare.
Require Import Arith_base.
Local Open Scope Z_scope.

Properties of the order relations on binary integers

# Trichotomy

Theorem Ztrichotomy_inf n m : {n < m} + {n = m} + {n > m}.

Theorem Ztrichotomy n m : n < m \/ n = m \/ n > m.

# Decidability of equality and order on Z

Notation dec_eq := Z.eq_decidable (only parsing).
Notation dec_Zle := Z.le_decidable (only parsing).
Notation dec_Zlt := Z.lt_decidable (only parsing).

Theorem dec_Zne n m : decidable (Zne n m).

Theorem dec_Zgt n m : decidable (n > m).

Theorem dec_Zge n m : decidable (n >= m).

Theorem not_Zeq n m : n <> m -> n < m \/ m < n.

# Relating strict and large orders

Notation Zgt_iff_lt := Z.gt_lt_iff (only parsing).
Notation Zge_iff_le := Z.ge_le_iff (only parsing).

Lemma Zle_not_lt n m : n <= m -> ~ m < n.

Lemma Zlt_not_le n m : n < m -> ~ m <= n.

Lemma Zle_not_gt n m : n <= m -> ~ n > m.

Lemma Zgt_not_le n m : n > m -> ~ n <= m.

Lemma Znot_ge_lt n m : ~ n >= m -> n < m.

Lemma Znot_lt_ge n m : ~ n < m -> n >= m.

Lemma Znot_gt_le n m: ~ n > m -> n <= m.

Lemma Znot_le_gt n m : ~ n <= m -> n > m.

Lemma not_Zne n m : ~ Zne n m -> n = m.

# Equivalence and order properties

Reflexivity

Notation Zeq_le := Z.eq_le_incl (only parsing).

#[global]
Hint Resolve Z.le_refl: zarith.

Antisymmetry

Notation Zle_antisym := Z.le_antisymm (only parsing).

Asymmetry

Notation Zlt_asym := Z.lt_asymm (only parsing).

Lemma Zgt_asym n m : n > m -> ~ m > n.

Irreflexivity

Notation Zlt_not_eq := Z.lt_neq (only parsing).

Lemma Zgt_irrefl n : ~ n > n.

Large = strict or equal

Notation Zlt_le_weak := Z.lt_le_incl (only parsing).
Notation Zle_lt_or_eq_iff := Z.lt_eq_cases (only parsing).

Lemma Zle_lt_or_eq n m : n <= m -> n < m \/ n = m.

Dichotomy

Notation Zle_or_lt := Z.le_gt_cases (only parsing).

Transitivity of strict orders

Lemma Zgt_trans n m p : n > m -> m > p -> n > p.

Mixed transitivity
Transitivity of large orders

Lemma Zge_trans n m p : n >= m -> m >= p -> n >= p.

#[global]
Hint Resolve Z.le_trans: zarith.

# Compatibility of order and operations on Z

## Successor

Compatibility of successor wrt to order

Lemma Zsucc_le_compat n m : m <= n -> Z.succ m <= Z.succ n.

Lemma Zsucc_lt_compat n m : n < m -> Z.succ n < Z.succ m.

Lemma Zsucc_gt_compat n m : m > n -> Z.succ m > Z.succ n.

#[global]
Hint Resolve Zsucc_le_compat: zarith.

Simplification of successor wrt to order
Special base instances of order

Notation Zlt_succ := Z.lt_succ_diag_r (only parsing).
Notation Zlt_pred := Z.lt_pred_l (only parsing).

Lemma Zgt_succ n : Z.succ n > n.

Lemma Znot_le_succ n : ~ Z.succ n <= n.

Relating strict and large order using successor or predecessor

Lemma Zgt_le_succ n m : m > n -> Z.succ n <= m.

Lemma Zle_gt_succ n m : n <= m -> Z.succ m > n.

Lemma Zle_lt_succ n m : n <= m -> n < Z.succ m.

Lemma Zlt_le_succ n m : n < m -> Z.succ n <= m.

Lemma Zgt_succ_le n m : Z.succ m > n -> n <= m.

Lemma Zlt_succ_le n m : n < Z.succ m -> n <= m.

Lemma Zle_succ_gt n m : Z.succ n <= m -> m > n.

Weakening order

Notation Zle_succ := Z.le_succ_diag_r (only parsing).
Notation Zle_pred := Z.le_pred_l (only parsing).
Notation Zlt_lt_succ := Z.lt_lt_succ_r (only parsing).
Notation Zle_le_succ := Z.le_le_succ_r (only parsing).

Lemma Zle_succ_le n m : Z.succ n <= m -> n <= m.

#[global]
Hint Resolve Z.le_succ_diag_r: zarith.
#[global]
Hint Resolve Z.le_le_succ_r: zarith.

Relating order wrt successor and order wrt predecessor
Relating strict order and large order on positive

Lemma Zlt_0_le_0_pred n : 0 < n -> 0 <= Z.pred n.

Lemma Zgt_0_le_0_pred n : n > 0 -> 0 <= Z.pred n.

Special cases of ordered integers

Lemma Zle_neg_pos : forall p q:positive, Zneg p <= Zpos q.

Lemma Zgt_pos_0 : forall p:positive, Zpos p > 0.

Lemma Zle_0_pos : forall p:positive, 0 <= Zpos p.

Lemma Zlt_neg_0 : forall p:positive, Zneg p < 0.

Lemma Zle_0_nat : forall n:nat, 0 <= Z.of_nat n.

#[global]
Hint Immediate Z.eq_le_incl: zarith.

Derived lemma

Compatibility of addition wrt to order

Notation Zplus_lt_le_compat := Z.add_lt_le_mono (only parsing).
Notation Zplus_le_lt_compat := Z.add_le_lt_mono (only parsing).
Notation Zplus_le_compat := Z.add_le_mono (only parsing).
Notation Zplus_lt_compat := Z.add_lt_mono (only parsing).

Lemma Zplus_gt_compat_l n m p : n > m -> p + n > p + m.

Lemma Zplus_gt_compat_r n m p : n > m -> n + p > m + p.

Lemma Zplus_le_compat_l n m p : n <= m -> p + n <= p + m.

Lemma Zplus_le_compat_r n m p : n <= m -> n + p <= m + p.

Lemma Zplus_lt_compat_l n m p : n < m -> p + n < p + m.

Lemma Zplus_lt_compat_r n m p : n < m -> n + p < m + p.

Compatibility of addition wrt to being positive

Notation Zplus_le_0_compat := Z.add_nonneg_nonneg (only parsing).

Simplification of addition wrt to order

## Multiplication

Compatibility of multiplication by a positive wrt to order
Simplification of multiplication by a positive wrt to being positive
Compatibility of multiplication by a positive wrt to being positive

Notation Zmult_le_0_compat := Z.mul_nonneg_nonneg (only parsing).
Notation Zmult_lt_0_compat := Z.mul_pos_pos (only parsing).
Notation Zmult_lt_O_compat := Z.mul_pos_pos (only parsing).

Lemma Zmult_gt_0_compat n m : n > 0 -> m > 0 -> n * m > 0.

Lemma Zmult_gt_0_le_0_compat n m : n > 0 -> 0 <= m -> 0 <= m * n.

Simplification of multiplication by a positive wrt to being positive

Lemma Zmult_le_0_reg_r n m : n > 0 -> 0 <= m * n -> 0 <= m.

Lemma Zmult_lt_0_reg_r n m : 0 < n -> 0 < m * n -> 0 < m.

Lemma Zmult_gt_0_lt_0_reg_r n m : n > 0 -> 0 < m * n -> 0 < m.

Lemma Zmult_gt_0_reg_l n m : n > 0 -> n * m > 0 -> m > 0.

## Square

Simplification of square wrt order

# Equivalence between inequalities

Notation Zle_plus_swap := Z.le_add_le_sub_r (only parsing).
Notation Zlt_plus_swap := Z.lt_add_lt_sub_r (only parsing).
Notation Zlt_minus_simpl_swap := Z.lt_sub_pos (only parsing).

Lemma Zeq_plus_swap n m p : n + p = m <-> n = m - p.

Lemma Zlt_0_minus_lt n m : 0 < n - m -> m < n.

Lemma Zle_0_minus_le n m : 0 <= n - m -> m <= n.

Lemma Zle_minus_le_0 n m : m <= n -> 0 <= n - m.

For compatibility
Notation Zlt_O_minus_lt := Zlt_0_minus_lt (only parsing).