create implication 1621 (3) -> 17th_century (61)
change category 1621 (3) -> meta
create implication 1779 (1) -> 18th_century (90)
change category 1779 (1) -> meta
create implication 12th_century_bc (3) -> ancient_art (2376)
create implication 13th_century_bc (1) -> ancient_art (2376)