simp only [header, Schema.names, Schema.sieve_eq_List_sieve]
η : Type u_η
dec_η : DecidableEq η
sch : Schema
t : Table sch
bs : List Bool
⊢ header (selectColumns1 t bs) <+ header t
η : Type u_η
dec_η : DecidableEq η
sch : Schema
t : Table sch
bs : List Bool
⊢ List.map Prod.fst (List.sieve bs sch) <+ List.map Prod.fst sch