Logic Rules - Boolean Network Models Step by Step

A gene's rule can combine several regulators with AND/OR; arrows carry the sign of each regulation.

highlighted = computed this step

A rule can combine several inputs

A gene often depends on more than one regulator. Here A is ON only when BOTH B and C are ON — a logical AND. The truth table lists the gene's next state for all 4 input combinations.

A_{\text{next}} = B \operatorname{AND} C

Arrows carry the sign of regulation

The wiring draws B and C activating A with pointed arrows. An activator uses a pointed arrowhead; a repressor uses a bar. Each arrow's sign is checked against the rule, so the picture cannot claim a regulation the table does not support. (An OR rule would wire the same two arrows but turn A ON if EITHER input is ON.)

\rightarrow \text{ activates}, \quad \dashv \text{ represses}