Perhaps you should try some spelling variations:
variational problem » variational problems (Expand search)
method variational » methods variational (Expand search), method variations (Expand search), without variational (Expand search)
decrease processes » disease processes (Expand search), defense processes (Expand search), decay processes (Expand search)
decrease decrease » decrease release (Expand search), disease decreases (Expand search), decrease sucrose (Expand search)
decrease toc » decrease of (Expand search), decrease the (Expand search), decrease on (Expand search)
toc decrease » to decrease (Expand search), the decrease (Expand search), not decrease (Expand search)

You may be able to get more results by adjusting your search query.

• The words AND, OR and NOT may confuse the search; try adding quotes: "(( decrease toc decrease decrease processes ) OR ( python AND method variational problem ))~".
• Adding a wildcard symbol may retrieve word variants: (( decrease toc decrease decrease processes ) OR ( python AND method variational problem ))*.