Assign different set operators to the characters in your LibreOffice Math formula. The individual operators are shown in the lower section of the Elements pane. Call the context menu in the Commands window to see an identical list of the individual functions. Any operators not found in the Elements pane have to be entered directly in the Commands window. You can also directly insert other parts of the formula even if symbols already exist for them.
After selecting the Set Operations item in the Elements pane, relevant icons will be shown in the lower part of this pane. Simply click a symbol to incorporate the operator in the formula being edited in the Commands window.