revisit the final part of OR only (#2757)
revisit the final part of OR only (#2757)

* revisit the final part of OR only

* rewrap

* change title

Co-authored-by: Wolf Lammen <01bc1a4c47e663dedda11e6a436c45c0e42fc206@gmail.com>
metamath/set.mm,metamath/set.mm,metamath/set.mm