Theorem: ncols_eq_header_length (Table/Proofs.lean)

State before:
η : Type u_η
dec_η : DecidableEq η
sch : Schema
⊢ ∀ (t : Table sch), ncols t = List.length (header t)
Tactic:
intro t
State after:
η : Type u_η
dec_η : DecidableEq η
sch : Schema
t : Table sch
⊢ ncols t = List.length (header t)

State before:
η : Type u_η
dec_η : DecidableEq η
sch : Schema
t : Table sch
⊢ ncols t = List.length (header t)
Tactic:
simp only [ncols, Schema.length_eq_List_length]
State after:
η : Type u_η
dec_η : DecidableEq η
sch : Schema
t : Table sch
⊢ List.length sch = List.length (header t)

State before:
η : Type u_η
dec_η : DecidableEq η
sch : Schema
t : Table sch
⊢ List.length sch = List.length (header t)
Tactic:
apply Eq.symm
State after:
case h
η : Type u_η
dec_η : DecidableEq η
sch : Schema
t : Table sch
⊢ List.length (header t) = List.length sch

State before:
case h
η : Type u_η
dec_η : DecidableEq η
sch : Schema
t : Table sch
⊢ List.length (header t) = List.length sch
Tactic:
apply List.length_map
State after:
no goals