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- T(3) = T(2) + 2*T(1) + n. It uses previous base cases therefore we don't need any more base cases.
- Base cases:
- n=1 : T(1) = 1 $\geq$ c*1*log1 for any c
- n=2 : T(2) = 1 $\geq$ c*2*log2 for c $\leq$ 1/2
- Step: We show that the inequality holds for some n $\geq$ $n_0$
- IH: Assume that T(k) $\geq$ c*k*log k
- T(n) = T($\lceil$n/2$\rceil$) + 2*T($\lceil$n/4$\rceil$) + n (IH on $\lceil$n/2$\rceil$ and $\lceil$n/4$\rceil$)
- T(n) $\geq$ c*$\lceil$n/2$\rceil$*log$\lceil$n/2$\rceil$ + 2*c*$\lceil$n/4$\rceil$*log$\lceil$n/4$\rceil$ + n
- n/2 $\leq$ $\lceil$n/2$\rceil$ and n/4 $\leq$ $\lceil$n/4$\rceil$ and n/4 < n/2
- c*n/2*log(n/4) + 2*c*n/4*log(n/4) + n
- c*(n/2+2*n/2)*log(n/4) + n
- c*n*log(n/4) + n
- c*n*logn -2*c*n + n
- c*n*logn -n(2*c - 1) $\geq$ c*n*logn
- -2c+1 $\geq$ 0
- 2c $\geq$ -1
- c$\leq$ 1/2
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