<P> \ smashtimes requires \ usepackage (unicode - math) and \ setmathfont (XITS Math) or another Open Type Math Font . </P> <P> ⇒ ⇐ (\ displaystyle \ Rightarrow \ Leftarrow) \ Rightarrow \ Leftarrow ⊥ (\ displaystyle \ bot) \ bot </P> <P> ↮ (\ displaystyle \ nleftrightarrow) \ nleftrightarrow </P> <P> \ textreferencemark Contradiction! </P>

What does the symbol a circle with a line through it mean