Smale's problems
Smale's problems are a list of eighteen unsolved problems in mathematics that was proposed by Steve Smale in 1998, republished in 1999. Smale composed this list in reply to a request from Vladimir Arnold, then vice-president of the International Mathematical Union, who asked several mathematicians to propose a list of problems for the 21st century. Arnold's inspiration came from the list of Hilbert's problems that had been published at the beginning of the 20th century.
Table of problems
| Problem | Brief explanation | Status | Year Solved |
| 1st | Riemann hypothesis: The real part of every non-trivial zero of the Riemann zeta function is 1/2. | – | |
| 2nd | Poincaré conjecture: Every simply connected, closed 3-manifold is homeomorphic to the 3-sphere. | 2003 | |
| 3rd | P versus NP problem: For all problems for which an algorithm can verify a given solution quickly, can an algorithm also find that solution quickly? | – | |
| 4th | Shub–Smale tau-conjecture on the integer zeros of a polynomial of one variable | – | |
| 5th | Can one decide if a Diophantine equation ƒ = 0 has an integer solution,, in time c for some universal constant c? That is, can the problem be decided in exponential time? | – | |
| 6th | Is the number of relative equilibria finite, in the n-body problem of celestial mechanics, for any choice of positive real numbers m1, ..., mn as the masses? | 2012 | |
| 7th | Algorithm for finding set of such that the function: is minimized for a distribution of N points on a 2-sphere. | – | |
| 8th | Extend the mathematical model of general equilibrium theory to include price adjustments | Gjerstad extends the deterministic model of price adjustment to a stochastic model and shows that when the stochastic model is linearized around the equilibrium the result is the autoregressive price adjustment model used in applied econometrics. He then tests the model with price adjustment data from a general equilibrium experiment. The model performs well in a general equilibrium experiment with two commodities. | 2013 |
| 9th | The linear programming problem: Find a strongly-polynomial time algorithm which for given matrix A ∈ Rm×n and b ∈ Rm decides whether there exists x ∈ Rn with Ax ≥ b. | – | |
| 10th | Pugh's closing lemma | 2016 | |
| 11th | Is one-dimensional dynamics generally hyperbolic? Can a complex polynomial be approximated by one of the same degree with the property that every critical point tends to a periodic sink under iteration? Can a smooth map be approximated by one which is hyperbolic, for all ? | 2007 | |
| 12th | For a closed manifold and any let be the topological group of diffeomorphisms of onto itself. Given arbitrary, is it possible to approximate it arbitrary well by such that it commutes only with its iterates? In other words, is the subset of all diffeomorphisms whose centralizers are trivial dense in ? | 2009 | |
| 13th | Hilbert's 16th problem: Describe relative positions of ovals originating from a real algebraic curve and as limit cycles of a polynomial vector field on the plane. | – | |
| 14th | Do the properties of the Lorenz attractor exhibit that of a strange attractor? | 2002 | |
| 15th | Do the Navier–Stokes equations in R3 always have a unique smooth solution that extends for all time? | – | |
| 16th | Jacobian conjecture: If The Jacobian determinant of F is a non-zero constant and k has characteristic 0, then F has an inverse function G : kN → kN, and G is regular. | – | |
| 17th | Solving polynomial equations in polynomial time in the average case | 2008-2016 | |
| 18th | Limits of intelligence | – |
In later versions, Smale also listed three additional problems, "that don’t seem important enough to merit a place on our main list, but it would still be nice to solve them:"
- Mean value problem
- Is the three-sphere a minimal set ?
- Is an Anosov diffeomorphism of a compact manifold topologically the same as the Lie group model of John Franks?