with elements(a,b,cnt) as
(
VALUES ('Элемент1','Элемент2', 1 . 0 ),
('Элемент1','Элемент3', 2 . 0 ),
('Элемент3','Элемент4', 1 . 0 ),
('Элемент4','Элемент5', 1 . 0 )

),
d0(a,b,cnt,his) as
(
SELECT t1.a,t1.b,t1.cnt,cast(t1.a||'^'||t1.b as varchar( 200 )) FROM elements t1
UNION ALL
SELECT t1.b,t1.a, 1 /t1.cnt,cast(t1.b||'^'||t1.a as varchar( 200 )) FROM elements t1
),
d1(a,b,cnt,lvl,his) as 
(
select d0.a,d0.b,cast(d0.cnt as double), 1 , his  from d0
UNION ALL
(
select t1.a,t2.a,case when t2.cnt= 0  then  0  else t1.cnt/t2.cnt end,t1.lvl+ 1 ,t1.his||'^'||t2.a from d1 as t1, d0 as t2 
where t1.b=t2.b and t1.a!=t2.a and  LOCATE(t2.a,t1.his)= 0  and  LOCATE(t1.a,t2.his)= 0   and t1.lvl< 10 
)

) select * from d1 ;