Parameterized complexity: Difference between revisions

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:A parameterized problem <math>L</math> is ''fixed-parameter tractable'' if the question &ldquo;<math>(x, k) \in L</math>?&rdquo; can be decided in running time <math>f(k) \cdot |x|^{O(1)}</math>, where <math>f</math> is an arbitrary function depending only on <math>k</math>. The corresponding complexity class is called '''FPT'''.

For example, there is an algorithm which solves the vertex cover problem in <math>O(kn + 1.274^k)</math> time, where <math>n</math> is the number of vertices and <math>k</math> is the size of the vertex cover. This provesmeans that vertex cover is fixed-

parameter tractable with respectthe tosize thisof the solution as the only parameter.

==W hierarchy==