let e2 ≝ \ 5a title="eclose" href="cic:/fakeuri.def(1)"\ 6•\ 5/a\ 6(\ 5a href="cic:/matita/tutorial/chapter8/blank.fix(0,1,3)"\ 6blank\ 5/a\ 6 ? re2) in
let n ≝ \ 5a href="cic:/matita/arithmetics/nat/nat.con(0,2,0)"\ 6S\ 5/a\ 6 (\ 5a href="cic:/matita/basics/list/length.fix(0,1,1)"\ 6length\ 5/a\ 6 ? (\ 5a href="cic:/matita/tutorial/chapter10/space_enum.def(5)"\ 6space_enum\ 5/a\ 6 Sig (\ 5a title="forget" href="cic:/fakeuri.def(1)"\ 6|\ 5/a\ 6\ 5a title="pair pi1" href="cic:/fakeuri.def(1)"\ 6\fst\ 5/a\ 6 e1|) (\ 5a title="forget" href="cic:/fakeuri.def(1)"\ 6|\ 5/a\ 6\ 5a title="pair pi1" href="cic:/fakeuri.def(1)"\ 6\fst\ 5/a\ 6 e2|))) in
let sig ≝ (\ 5a href="cic:/matita/tutorial/chapter10/occ.def(7)"\ 6occ\ 5/a\ 6 Sig e1 e2) in
let e2 ≝ \ 5a title="eclose" href="cic:/fakeuri.def(1)"\ 6•\ 5/a\ 6(\ 5a href="cic:/matita/tutorial/chapter8/blank.fix(0,1,3)"\ 6blank\ 5/a\ 6 ? re2) in
let n ≝ \ 5a href="cic:/matita/arithmetics/nat/nat.con(0,2,0)"\ 6S\ 5/a\ 6 (\ 5a href="cic:/matita/basics/list/length.fix(0,1,1)"\ 6length\ 5/a\ 6 ? (\ 5a href="cic:/matita/tutorial/chapter10/space_enum.def(5)"\ 6space_enum\ 5/a\ 6 Sig (\ 5a title="forget" href="cic:/fakeuri.def(1)"\ 6|\ 5/a\ 6\ 5a title="pair pi1" href="cic:/fakeuri.def(1)"\ 6\fst\ 5/a\ 6 e1|) (\ 5a title="forget" href="cic:/fakeuri.def(1)"\ 6|\ 5/a\ 6\ 5a title="pair pi1" href="cic:/fakeuri.def(1)"\ 6\fst\ 5/a\ 6 e2|))) in
let sig ≝ (\ 5a href="cic:/matita/tutorial/chapter10/occ.def(7)"\ 6occ\ 5/a\ 6 Sig e1 e2) in