Scenario on some assign activity:
1) Create 4 '==' (equal) elements
2) Attach anything to their inputs (for example number literals)
3) Create 3 OR elements
4) Attach as follows 
   equal_1->OR_1
   equal_2->OR_1
   equal_3->OR_2
   equal_4->OR_2
   OR_1->OR_3
   OR_2->OR_3
5) Go to design view, then get back to mapper view, three ORs are combined into one big (which is nice)
6) Remove literals attached to equal_3 and equal_4, then remove these equals
7) Do the same as in step 5
both equals removed in 6) are still on place, OR is not reduced to 2 elements. BPEL is not compiling... I had to remove
the assigns manually from the text editor.