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  2. Subset sum problem - Wikipedia

    en.wikipedia.org/wiki/Subset_sum_problem

    Let A be the sum of the negative values and B the sum of the positive values; the number of different possible sums is at most B-A, so the total runtime is in (()). For example, if all input values are positive and bounded by some constant C , then B is at most N C , so the time required is O ( N 2 C ) {\displaystyle O(N^{2}C)} .

  3. Nielsen–Schreier theorem - Wikipedia

    en.wikipedia.org/wiki/Nielsen–Schreier_theorem

    The free group G = π 1 (X) has n = 2 generators corresponding to loops a,b from the base point P in X.The subgroup H of even-length words, with index e = [G : H] = 2, corresponds to the covering graph Y with two vertices corresponding to the cosets H and H' = aH = bH = a −1 H = b − 1 H, and two lifted edges for each of the original loop-edges a,b.

  4. Partition problem - Wikipedia

    en.wikipedia.org/wiki/Partition_problem

    Equal-cardinality partition is a variant in which both parts should have an equal number of items, in addition to having an equal sum. This variant is NP-hard too. [5]: SP12 Proof. Given a standard Partition instance with some n numbers, construct an Equal-Cardinality-Partition instance by adding n zeros. Clearly, the new instance has an equal ...

  5. Word (group theory) - Wikipedia

    en.wikipedia.org/wiki/Word_(group_theory)

    For example, if x, y and z are elements of a group G, then xy, z −1 xzz and y −1 zxx −1 yz −1 are words in the set {x, y, z}. Two different words may evaluate to the same value in G, [1] or even in every group. [2] Words play an important role in the theory of free groups and presentations, and are central objects of study in ...

  6. Word problem for groups - Wikipedia

    en.wikipedia.org/wiki/Word_problem_for_groups

    That is, if is a finitely presented group that contains an isomorphic copy of every finitely presented group with solvable word problem, then itself must have unsolvable word problem. Remark: Suppose G = X | R {\displaystyle G=\langle X\,|\,R\rangle } is a finitely presented group with solvable word problem and H {\displaystyle H} is a finite ...

  7. For loop - Wikipedia

    en.wikipedia.org/wiki/For_loop

    INT sum sq := 0; FOR i WHILE print(("So far:", i, new line)); # Interposed for tracing purposes. # sum sq ≠ 70↑2 # This is the test for the WHILE # DO sum sq +:= i↑2 OD Subsequent extensions to the standard ALGOL 68 allowed the to syntactic element to be replaced with upto and downto to achieve a small optimization.

  8. Burnside's lemma - Wikipedia

    en.wikipedia.org/wiki/Burnside's_lemma

    Burnside's lemma can compute the number of rotationally distinct colourings of the faces of a cube using three colours.. Let X be the set of 3 6 possible face color combinations that can be applied to a fixed cube, and let the rotation group G of the cube act on X by moving the colored faces: two colorings in X belong to the same orbit precisely when one is a rotation of the other.

  9. Conditional (computer programming) - Wikipedia

    en.wikipedia.org/wiki/Conditional_(computer...

    If-then-else flow diagram A nested if–then–else flow diagram. In computer science, conditionals (that is, conditional statements, conditional expressions and conditional constructs) are programming language constructs that perform different computations or actions or return different values depending on the value of a Boolean expression, called a condition.