In
computer science,
parameterized complexity is a branch of
computational complexity theory that focuses on classifying
computational problems according to their inherent difficulty with respect to
multiple parameters of the input or output. The complexity of a problem is then measured as a
function in those parameters. This allows the classification of
NP-hard problems on a finer scale than in the classical setting, where the complexity of a problem is only measured by the number of bits in the input. The first systematic work on parameterized complexity was done by .