Example of using rule sets to write higher order logic

sets.md

wxs@wxs-mbp yara % cat rules/sets.yara
rule a0 { condition: false }
rule a1 { condition: true }
rule b { condition: 1 of (a*) }
rule c { condition: 2 of (a*) }
rule d { condition: 50% of (a*) }
rule e { condition: 1 of (a1) }
rule f { condition: all of (a1, e) }
wxs@wxs-mbp yara %

wxs@wxs-mbp yara % ./yara rules/sets.yara /bin/ls
a1 /bin/ls
b /bin/ls
d /bin/ls
e /bin/ls
f /bin/ls
wxs@wxs-mbp yara %