. 2015 May 21;31(18):2999–3007. doi: 10.1093/bioinformatics/btv314

Table 1.

The relationship between the OR Boolean update function $B (x_{1}, x_{2})$ and its continuous homologue ${\bar{B}}^{I} ({\bar{x}}_{1}, {\bar{x}}_{2})$ , obtained by multivariate polynomial interpolation (Wittmann et al., 2009), is illustrated with the help of a truth table

$x_{1}$	$x_{2}$	$B (x_{1}, x_{2})$	${\bar{B}}^{I} ({\bar{x}}_{1}, {\bar{x}}_{2}) = ...$
0	0	0	$0 \cdot (1 - {\bar{x}}_{1}) \cdot (1 - {\bar{x}}_{2}) +$
0	1	1	$1 \cdot (1 - {\bar{x}}_{1}) \cdot {\bar{x}}_{2} +$
1	0	1	$1 \cdot {\bar{x}}_{1} \cdot (1 - {\bar{x}}_{2}) +$
1	1	1	$1 \cdot {\bar{x}}_{1} \cdot {\bar{x}}_{2}$

Note: For every combination of the Boolean variables x₁ and x₂, a term is added to ${\bar{B}}^{I} ({\bar{x}}_{1}, {\bar{x}}_{1}$ ) depending on $B (x_{1}, x_{2})$ .