今天是希爾伯特的忌日

特此紀念

Hilbert's twenty-three problems are:

Problem	Brief explanation	Status	Year Solved
1st	The continuum hypothesis (that is, there is no set whose cardinality is strictly between that of the integers and that of the real numbers)	Resolved. Proven to be impossible to prove or disprove within the Zermelo–Fraenkel set theory with or without the Axiom of Choice (provided the Zermelo–Fraenkel set theory with or without the Axiom of Choice is consistent, i.e., contains no two theorems such that one is a negation of the other). There is general consensus that this solves the problem, although there have been proposals which would give a definitive truth value (see Ω-logic).	1963
2nd	Prove that the axioms of arithmetic are consistent.	There is no consensus on whether results of Gödel and Gentzen give a solution to the problem as stated by Hilbert. Gödel'ssecond incompleteness theorem, proved in 1931, shows that no proof of its consistency can be carried out within arithmetic itself. Gentzen proved in 1936 that the consistency of arithmetic follows from the well-foundedness of the ordinal ε₀.	1936?
3rd	Given any two polyhedra of equal volume, is it always possible to cut the first into finitely many polyhedral pieces which can be reassembled to yield the second?	Resolved. Result: no, proved using Dehn invariants.	1900
4th	Construct all metrics where lines are geodesics.	Too vague to be stated resolved or not.[n 1]	–
5th	Are continuous groups automatically differential groups?	Resolved by Andrew Gleason, depending on how the original statement is interpreted. If, however, it is understood as an equivalent of the Hilbert–Smith conjecture, it is still unsolved.	1953?
6th	Mathematical treatment of the axioms of physics	Partially resolved depending on how the original statement is interpreted.[13] In particular, in a further explanation Hilbert proposed two specific problems: (i) axiomatic treatment of probability with limit theorems for foundation of statistical physics and (ii) the rigorous theory of limiting processes "which lead from the atomistic view to the laws of motion of continua". Kolmogorov’s axiomatics (1933) is now accepted as standard. There is some success on the way from the "atomistic view to the laws of motion of continua".[14]	1933-2002?
7th	Is a b transcendental, for algebraic a ≠ 0,1 and irrational algebraic b ?	Resolved. Result: yes, illustrated by Gelfond's theorem or the Gelfond–Schneider theorem.	1935
8th	The Riemann hypothesis ("the real part of any non-trivial zero of the Riemann zeta function is ½") and other prime number problems, among them Goldbach's conjecture and the twin prime conjecture	Unresolved.	–
9th	Find the most general law of the reciprocity theorem in any algebraic number field.	Partially resolved.[n 2]	–
10th	Find an algorithm to determine whether a given polynomial Diophantine equation with integer coefficients has an integer solution.	Resolved. Result: impossible, Matiyasevich's theorem implies that there is no such algorithm.	1970
11th	Solving quadratic forms with algebraic numerical coefficients.	Partially resolved.[citation needed]	–
12th	Extend the Kronecker–Weber theorem on abelian extensions of the rational numbers to any base number field.	Unresolved.	–
13th	Solve 7-th degree equation using continuous functions of two parameters.	The problem was partially solved by Vladimir Arnold based on work by Andrei Kolmogorov. [n 4]	1957
14th	Is the ring of invariants of an algebraic group acting on a polynomial ring always finitely generated?	Resolved. Result: no, counterexample was constructed by Masayoshi Nagata.	1959
15th	Rigorous foundation of Schubert's enumerative calculus.	Partially resolved.[citation needed]	–
16th	Describe relative positions of ovals originating from a real algebraic curve and as limit cycles of a polynomial vector field on the plane.	Unresolved.	–
17th	Express a nonnegative rational function as quotient of sums of squares.	Resolved. Result: yes, due to Emil Artin. Moreover, an upper limit was established for the number of square terms necessary.[citation needed]	1927
18th	(a) Is there a polyhedron which admits only an anisohedral tiling in three dimensions? (b) What is the densest sphere packing?	(a) Resolved. Result: yes (by Karl Reinhardt). (b) Widely believed to be resolved, by computer-assisted proof (by Thomas Callister Hales). Result: Highest density achieved by close packings, each with density approximately 74%, such as cubic close packing and hexagonal close packing.[n 5][citation needed]	(a) 1928 (b) 1998
19th	Are the solutions of regular problems in the calculus of variations always necessarily analytic?	Resolved. Result: yes, proven by Ennio de Giorgi and, independently and using different methods, by John Forbes Nash.	1957
20th	Do all variational problems with certain boundary conditions have solutions?	Resolved. A significant topic of research throughout the 20th century, culminating in solutions[citation needed] for the non-linear case.	?
21st	Proof of the existence of linear differential equations having a prescribed monodromic group	Resolved. Result: Yes or no, depending on more exact formulations of the problem.[citation needed]	?
22nd	Uniformization of analytic relations by means of automorphic functions	Resolved.[citation needed]	?
23rd	Further development of the calculus of variations	Unresolved.	–