match_recognize

with t as
(select 1 id11, 10 id12, 1 id21, 10 id22 from dual union all
 select 2, null, 2, null from dual union all
 select 3, null, 15, null from dual union all
 select 4, null, 9, null from dual)
select
  id11
from t
match_recognize
(
  order by id11, id21
  measures classifier() as cls
  all rows per match
  pattern (a b+)
  define
    a as id12 is not null and id22 is not null,
    b as id11 <= prev(id12) and id11 >= prev(id11) and id21 <= prev(id22) and id21 >= prev(id21)
)
where cls = 'B'