In eXpress, Lambda Search Criteria are used to constrain the degree to which Serial Replacement Option (def:Serial Replacement) is to be permitted when assessing a design or diagnostic strategy's fault isolation capability. These criteria allow the Analyst to limit the total number of serial replacements and/or only allow serial replacement when the isolated failure probability for an itemexceeds a certain relative threshold. The Analyst can set these criteria in the settings dialogs for the Fault Isolation Report Setup and the Subset FD/FI Statistics Report.
Comparison Method - The Comparison Method is used to specify whether the highest isolated item failure probability is to be compared with the next highest isolated item failure probability (the "Next Highest Item" setting) or the sum of all remaining isolated item failure probabilities (the "Sum Remaining Items" setting).
Comparison Ratio -The Comparison Ratio is used to specify the relative threshold that must be exceeded in order for Serial Replacement to be applied. For example, if the Comparison Ratio is set to 10, then the highest failure probability associated with an unrepaired item in the fault groups must exceed the Test limit specified by the Comparison Method by a ratio of 10 to 1.
Maximum Counted - The Maximum Counted option specifies the maximum number of serial replacements allowed (i.e., the maximum number of applications of lambda search). Note: This option is not available in the Subset FD/FI Statistics Report, since this report only provides metrics describing a single replacement.
