a plurality of evaluator modules that each evaluates at least one evaluation function to generate an evaluation of how well parsing results output by a parsing engine match corresponding labeled results, wherein the evaluation of how well a parsing result output by a parsing engine matches a corresponding labeled results expresses a plurality of differences between the parsing results and the labeled results, the differences including: grouping difference being different grouping of ink components, structural difference being different relationships among ink components, and attribute difference being different attributes associated with ink components; and

a searcher module that obtains from each of the plurality of evaluator modules the evaluations of how well the parsing results output by the parsing engines match the corresponding labeled results, wherein the searcher module generates a set of parsing-engine parameters that is based on the plurality of evaluations obtained from the plurality of evaluator modules such that the set of parsing-engine parameters optimizes an ink parser's performance.