input: 2; output: 2; aliases: LETTER = ([GREEK SMALL LETTER ALPHA WITH TONOS]-[GREEK THETA SYMBOL] | [GREEK PHI SYMBOL] | [GREEK PI SYMBOL] | [GREEK KAPPA SYMBOL]-[GREEK LETTER YOT] | [GREEK SMALL LETTER ALPHA WITH PSILI]-@"1FFF) ; expressions: {LETTER}[GREEK SMALL LETTER BETA][GREEK SMALL LETTER BETA] => \1 [GREEK BETA SYMBOL] [GREEK BETA SYMBOL] ; {LETTER}[GREEK SMALL LETTER BETA] => \1 [GREEK BETA SYMBOL] ; . => \1;