 Expert systems restricted themselves to a small domain of specific knowledge ( thus avoiding the commonsense knowledge problem ) and their simple design made it relatively easy for programs to be built and then modified once they were in place . All in all , the programs proved to be useful : something that AI had not been able to achieve up to this point . 
 Expert systems restricted themselves to a small domain of specific knowledge ( thus avoiding the commonsense knowledge problem ) and their simple design made it relatively easy for programs to be built and then modified once they <a href='uninflect' title='1'><mark>were</mark></a> in place . All in all , the programs proved to be useful : something that AI had <a href='negative_concord' title='2'><mark>not</mark></a><a href='negative_concord' title='3'><mark>been</mark></a> able to achieve up to this point . 
Expert systems restricted themselves to a small domain of specific knowledge ( thus avoiding the commonsense knowledge problem ) and their simple design made it relatively easy for programs to b built and then modified once they was in place . alll in all , the programs proved to be useful : somthing dat AI had ain't able to achieve up to dis point .