diff options
Diffstat (limited to 'mathcomp')
| -rw-r--r-- | mathcomp/ssreflect/seq.v | 17 |
1 files changed, 17 insertions, 0 deletions
diff --git a/mathcomp/ssreflect/seq.v b/mathcomp/ssreflect/seq.v index fa3bf25..d562f25 100644 --- a/mathcomp/ssreflect/seq.v +++ b/mathcomp/ssreflect/seq.v @@ -2623,6 +2623,23 @@ elim: ss => //= s ss IHss in i *; rewrite subn_eq0 nth_cat. by have [//|le_s_i] := ltnP; rewrite subnDA subSn /=. Qed. +Lemma reshape_index_leq sh i1 i2 + (r1 := reshape_index sh i1) (c1 := reshape_offset sh i1) + (r2 := reshape_index sh i2) (c2 := reshape_offset sh i2) : + i2 < sumn sh -> + (i1 <= i2) = ((r1 < r2) || ((r1 == r2 ) && (c1 <= c2))). +Proof. +rewrite {}/r1 {}/c1 {}/r2 {}/c2 /reshape_offset /reshape_index. +elim: sh i1 i2 => [i1 i2 |] //= s0 s IHs i1 i2. +rewrite !subn_eq0. +case: (ltnP i1 s0) => Hi1s0 //= ; case: (ltnP i2 s0) => Hi2s0 //=. +- by rewrite !subn0. +- by have := leq_trans Hi1s0 Hi2s0 => /ltnW ->. +- by have := leq_trans Hi2s0 Hi1s0; rewrite ltnNge => /negbTE ->. +- rewrite -leq_subLR ltnS eqSS (subSn Hi1s0) (subSn Hi2s0). + by rewrite -{2}(subnK Hi2s0) addnC -leq_subLR !subnDA => /IHs ->. +Qed. + End Flatten. Prenex Implicits flatten shape reshape. |