There are 100000 documents in the database. The statistic data for one query is shown in the following table. The precision is 20%.
Relevant | Irrelevant | |
---|---|---|
Retrieved | 10000 | 40000 |
Not Retrieved | 30000 | 20000 |
In the master method, we define T(N) in the recursive form T(N)=aT(N/b)+f(N). It means that the algorithm divides the problem into a parts, with each part being b1 the size of the original. It costs f(N) to gather results from subproblems and to derive its own result.
A Las Vegas algorithm is a randomized algorithm that always gives the correct result, however the runtime of a Las Vegas algorithm differs depending on the input.
A Monte Carlo algorithm is a randomized algorithm whose output may be incorrect with a certain (typically small) probability. The running time for the algorithm is fixed however.
Then if a Monte Carlo algorithm runs in O(n2) time, with the probability 50% of producing a correct solution, then there must be a Las Vegas algorithm that can get a solution in O(n2) time in expectation.
To evaluate the prefix-sums of a sequence of 16 numbers by the parallel algorithm with Balanced Binary Trees, C(1,3) is found before C(2,1).
C(h,i)=∑k=1aA(k) where (0,a) is the rightmost descendant leaf of node (h,i).
In a Turnpike Reconstruction problem, given the distance set D={1,2,2,3,3,3,5,5,6,8}, there must be a point placed at 6.
Suppose we have a potential function Φ such that for all Φ(Di)≥Φ(D0) for all i, but Φ(D0)=0. Then there exists a potential Φ′ such that Φ′(D0)=0, Φ′(Di)≥0 for all i≥1, and the amortized costs using Φ′ are the same as the amortized costs using Φ.
Suppose that T is an minimum spanning tree of the graph G, and S is a connected sub-graph of G. Then T∩S must belong to an minimum spanning tree of S.
Considering leftist heaps of n nodes, the Merge operation has a higher time complexity than the DeleteMin operation.
The height of an AVL tree of 30 nodes can be 5. (The height of an empty tree is defined to be -1)
NP-complete problems are the hardest problems in NP-hard problems in terms of computational complexity.
For an approximation algorithm for a minimization problem, given that the algorithm does not guarantee to find the optimal solution, the best approximation ratio possible to achieve is a constant α>1.
Suppose that the replacement selection is applied to generate longer runs with a priority queue of size 3. Given the sequence of numbers { 81, 94, 11, 96, 12, 99, 17,35,28, 58, 41,75,15}. Then 99 will belong to the 1st run.
Without any assumptions on the distances, if P = NP, there is no ρ-approximation for TSP (Travelling Salesman Problem) for any ρ≥1.