【计】 four-colour conjecture
four
【医】 quadri-; Quat; quattuor; tetra-
color; expression; hue; kind; quality; scene; woman's looks
【医】 chrom-; chromato-; chromo-; color
confer; conjecture; guess; presume; speculate; surmise
【计】 conjecture
【经】 guess work
issue; problem; question; trouble
【计】 sieve problem
【经】 subject