Equivalences

noun

1. The condition of being equivalent or essentially equal.
2. An equivalence relation; ≡; ~
3. The relationship between two propositions that are either both true or both false.
4. The quantity of the combining power of an atom, expressed in hydrogen units; the number of hydrogen atoms can combine with, or be exchanged for; valency.
5. A Boolean operation that is TRUE when both input variables are TRUE or both input variables are FALSE, but otherwise FALSE; the XNOR function.