Metamath Proof Explorer


Theorem seq1p

Description: Removing the first term from a sequence. (Contributed by NM, 17-Mar-2005) (Revised by Mario Carneiro, 27-May-2014)

Ref Expression
Hypotheses seqsplit.1 ⊢ φ ∧ x ∈ S ∧ y ∈ S → x + ˙ y ∈ S
seqsplit.2 ⊢ φ ∧ x ∈ S ∧ y ∈ S ∧ z ∈ S → x + ˙ y + ˙ z = x + ˙ y + ˙ z
seqsplit.3 ⊢ φ → N ∈ ℤ ≥ M + 1
seq1p.4 ⊢ φ → M ∈ ℤ
seq1p.5 ⊢ φ ∧ x ∈ M … N → F ⁡ x ∈ S
Assertion seq1p ⊢ φ → seq M + ˙ F ⁡ N = F ⁡ M + ˙ seq M + 1 + ˙ F ⁡ N

Proof

Step Hyp Ref Expression
1 seqsplit.1 ⊢ φ ∧ x ∈ S ∧ y ∈ S → x + ˙ y ∈ S
2 seqsplit.2 ⊢ φ ∧ x ∈ S ∧ y ∈ S ∧ z ∈ S → x + ˙ y + ˙ z = x + ˙ y + ˙ z
3 seqsplit.3 ⊢ φ → N ∈ ℤ ≥ M + 1
4 seq1p.4 ⊢ φ → M ∈ ℤ
5 seq1p.5 ⊢ φ ∧ x ∈ M … N → F ⁡ x ∈ S
6 uzid ⊢ M ∈ ℤ → M ∈ ℤ ≥ M
7 4 6 syl ⊢ φ → M ∈ ℤ ≥ M
8 1 2 3 7 5 seqsplit ⊢ φ → seq M + ˙ F ⁡ N = seq M + ˙ F ⁡ M + ˙ seq M + 1 + ˙ F ⁡ N
9 seq1 ⊢ M ∈ ℤ → seq M + ˙ F ⁡ M = F ⁡ M
10 4 9 syl ⊢ φ → seq M + ˙ F ⁡ M = F ⁡ M
11 10 oveq1d ⊢ φ → seq M + ˙ F ⁡ M + ˙ seq M + 1 + ˙ F ⁡ N = F ⁡ M + ˙ seq M + 1 + ˙ F ⁡ N
12 8 11 eqtrd ⊢ φ → seq M + ˙ F ⁡ N = F ⁡ M + ˙ seq M + 1 + ˙ F ⁡ N