3.7.4 Master Theorem

Knowledge Base > Algorithm > Recurrence


Master theorem method provides us a ’cookbook’ method for solving recurrences of the form

           n
T(n) = a⋅T(b-)+ f(n)
, where a 1 and b > 1 are constants and f(n) is an asymptotically positive function.[1]

Theorem 3.7.4.1. Master Theorem Let a 1 and b > 1 be constants, let f(n) be a function, and let T(n) be defined on the negative integers by the recurrence

T(n) = a⋅T(n-)+ f(n)
           b
Then T(n) can be bounded asymptotically as follows,
          logb(a-ε)                         logba
f(n) = O (n      ),∃ε > 0   ⇒     T(n) = Θ (n   )
   f(n) = Θ (nlogba),∃ε > 0  ⇒     T(n) = Θ (nlogba ⋅lg n)
f(n) = Ω (nlogb(a+ε)),∃ε > 0 AND
     n-
a ⋅f(b) ≤ c ⋅f (n ),∃c < 1,n   ⇒     ∞ ⇒ T (n) = Θ(f(n)) (3.7.4)
Proof>