Crossword clues for the word: SETTHEORY The word SETTHEORY has appeared as an answer to at least 7 crossword clues on different crossword puzzles. Crossword clues for SETTHEORY Showing 1 to 7 of 7 results Clue(s) Branch of mathematics that uses union and intersection operations Branch of mathematics with Venn diagrams Cantor was behind this fixed idea Field with intersections and unions Firm proposition? Math major's class Notions about backdrops?