A method of improving integrity of a computer system , the method comprising the computer system: executing a certifiable software application composed of static program instructions executed sequentially to process input data to produce an output on which the computer system is configured to operate, the certifiable software application being certifiable for the computer system according to a certification standard; executing a qualifiable software application during execution of the certifiable software application, the qualifiable software application using a model iteratively built using a machine learning algorithm to process the input data to produce a corresponding output that corresponds to the output from the certifiable software application, the qualifiable software application being non-certifiable for the computer system according to the certification standard; cross-checking the output from the certifiable software application by comparison with the corresponding output from the qualifiable software application to verify the output from the certifiable software application, and thereby improve integrity of the computer system; and generating an alert that the output from the certifiable software application is unverified when the comparison indicates that the output from the certifiable software application differs from the corresponding output from the qualifiable software application by more than a threshold, wherein the output from the certifiable software application is verified when the comparison indicates that the output from the certifiable software application differs from the corresponding output from the qualifiable software application by no more than the threshold, and the method further comprises the computer system: operating on the output from the certifiable software application on which the computer system is configured to operate. executing a certifiable software application composed of static program instructions executed sequentially to process input data to produce an output on which the computer system is configured to operate, the certifiable software application being certifiable for the computer system according to a certification standard; executing a qualifiable software application during execution of the certifiable software application, the qualifiable software application using a model iteratively built using a machine learning algorithm to process the input data to produce a corresponding output that corresponds to the output from the certifiable software application, the qualifiable software application being non-certifiable for the computer system according to the certification standard; cross-checking the output from the certifiable software application by comparison with the corresponding output from the qualifiable software application to verify the output from the certifiable software application, and thereby improve integrity of the computer system; and generating an alert that the output from the certifiable software application is unverified when the comparison indicates that the output from the certifiable software application differs from the corresponding output from the qualifiable software application by more than a threshold, wherein the output from the certifiable software application is verified when the comparison indicates that the output from the certifiable software application differs from the corresponding output from the qualifiable software application by no more than the threshold, and the method further comprises the computer system: operating on the output from the certifiable software application on which the computer system is configured to operate. <EOS>