(quantum mechanics) A method of reducing high-order derivatives to a combinatorics problem, used extensively in quantum field theory to reduce arbitrary products of creation and annihilation operators to sums of products of pairs of these operators.

(computing theory) A theorem that establishes a limit on the extent to which an algorithm can decide whether certain mathematical expressions are equal.

(politics) A theorem stating that no voting system can be perfectly fair in all circumstances

(logic) A theorem stating that, in any formal system F with Peano arithmetic, for any formula P, if it is provable in F that "if P is provable in F then P is true", then P is provable in F.

(mathematics) A theorem stating that any non-singular algebraic curve defined by algebraic number coefficients represents a compact Riemann surface which is a ramified covering of the Riemann sphere, ramified at three points only.

(economics) A theorem stating that, if trade in an externality is possible and there are sufficiently low transaction costs, bargaining will lead to a Pareto efficient outcome regardless of the initial allocation of property.

plural of deduction theorem

plural of Sylow theorem

(mathematics) Any of a collection of theorems of finite group theory that give detailed information about the number of subgroups of fixed order that a given finite group contains.

(mathematics) A statement in algebraic geometry concerning the number of common zeros of n polynomials in n indeterminates. In its original form, the theorem states that in general the number of common zeros equals the product of the degrees of the polynomials.