# Index

X chromosomes

and randomness in females, 1014

X-ray crystallography, 993

X-ray diffraction patterns, 1082

Xerographic printing, 1195

XML

and computer communication, 1182

`Xor`

axioms for, 803

calculus of expressions, 1170

confluence of, 1037

DNF representation of, 1096

emulated by rule 30, 703

lower bounds on in DNF, 1143

size of formula for, 1096

table for, 806

words in languages for, 1173

Xor rules

see also Additive cellular automata

see also Rule 90