Two theoretical genetic strains of a virus (a⁻b⁻c⁻ and a⁺b⁺c⁺) were used to simultaneously infect a culture of host bacteria. Of 10,000 plaques scored, the following genotypes were observed. Determine the genetic map of these three genes on the viral chromosome. Decide whether interference was positive or negative. a⁺ b⁺ c⁺ 4100 a⁻ b⁺ c⁻ 160 a⁻ b⁻ c⁻ 3990 a⁺ b⁻ c⁺ 140 a⁺ b⁻ c⁻ 740 a⁻ b⁻ c⁺ 90 a⁻ b⁺ c⁺ 670 a⁺ b⁺ c⁻ 110