Initial assignment rules and repeated assignment rules cannot create explicit or implicit algebraic loops (for example, ''x = y'' and ''y = x''). Implicit references to compartments occur when referencing a species in concentration. The following rules introduce algebraic loops into the model: \n<a href="matlab: helpview([docroot '/toolbox/simbio/simbio.map'], 'simbiology_evaluationOrderOfRules')">Click here</a> for more information.