Table 4.

A scenario which shows an interaction pattern between two markers generated by a simple rule “$I(m1<2)\ast I(m2>1)\to$ – else +”

Genotype–phenotype				Allele coding and m1*m2
m1/m2	BB	Bb	bb	m1/m2	0	1	2
AA	+	+	+	0	0	0	0
Aa	–	+	+	1	0	1	2
aa	–	+	+	2	0	2	4

The standard multiplicative formulation ($m1\times m2$) cannot adequately represent this interaction and other terms would be needed in the model (additive, additive $\times$ additive, additive $\times$ dominance, dominance $\times$ dominance, see factorial model in [59, 60])