" Instead of pursuing the most imminent and real threats to our future -- terrorism -- this Bush administration chose to settle old scores , " he said .
" Instead of pursuing the most imminent and real threats - international terrorists , " Graham said , " this Bush administration chose to settle old scores . "
-computer iteratively recalculates the system state as it changes over time  -macro-level: system dynamics models  micro-level: agent-based models, cellular automate, micro-simulation. sometimes called spatial simulation models