In applied mathematics and dynamical system theory, Lyapunov vectors, named after Aleksandr Lyapunov, describe characteristic expanding and contracting directions of a dynamical system.
 They have been used in predictability analysis and as initial perturbations for ensemble forecasting in numerical weather prediction.
 In modern practice they are often replaced by bred vectors for this purpose.
In mathematics, the Lyapunov–Schmidt reduction or Lyapunov–Schmidt construction is used to study solutions to nonlinear equations in the case when the implicit function theorem does not work.
 It permits the reduction of infinite-dimensional equations in Banach spaces to finite-dimensional equations.
 It is named after Aleksandr Lyapunov and Erhard Schmidt.
In mathematics, the Lyapunov time is the characteristic timescale on which a dynamical system is chaotic.
 It is named after the Russian mathematician Aleksandr Lyapunov.
 It is defined as the inverse of a system's largest Lyapunov exponent.
The Lyapunov–Malkin theorem (named for Aleksandr Lyapunov and ) is a mathematical theorem detailing nonlinear stability of systems.
In the theory of ordinary differential equations (ODEs), Lyapunov functions are scalar functions that may be used to prove the stability of an equilibrium of an ODE.
 Named after the Russian mathematician Aleksandr Mikhailovich Lyapunov, Lyapunov functions (also called the Lyapunov’s second method for stability) are important to stability theory of dynamical systems and control theory.
 A similar concept appears in the theory of general state space Markov chains, usually under the name Foster–Lyapunov functions.
In algebraic geometry and algebraic topology, a branch of mathematics, A homotopy theory is a way to apply the techniques of algebraic topology, specifically homotopy, to algebraic varieties and, more generally, to schemes.
 The theory is due to Fabien Morel and Vladimir Voevodsky.
 The underlying idea is that it should be possible to develop a purely algebraic approach to homotopy theory by replacing the unit interval [0, 1] , which is not an algebraic variety, with the affine line A , which is.
 The theory requires a substantial amount of technique to set up, but has spectacular applications such as Voevodsky's construction of the derived category of mixed motives and the proof of the Milnor and Bloch-Kato conjectures.
Vladimir Alexandrovich Voevodsky ( ; Russian: Влади́мир Алекса́ндрович Воево́дский , 4 June 1966 - 30 September 2017) was a Russian mathematician.
 His work in developing a homotopy theory for algebraic varieties and formulating motivic cohomology led to the award of a Fields Medal in 2002.
 He is also known for the proof of the Milnor conjecture and motivic Bloch-Kato conjectures and for the univalent foundations of mathematics and homotopy type theory.
Lyapunov is a lunar crater named for Aleksandr Lyapunov that is located along the east-northeastern limb of the Moon, and is viewed from the side by observers on Earth.
 The eastern rim of this crater just falls into the section of the Moon called the far side, and visibility of this formation is affected by libration.
In algebraic geometry, the "h" topology is a Grothendieck topology introduced by Vladimir Voevodsky to study the homology of schemes.
 It has several variants, such as the "qfh" and "cdh" topologies.
Aleksandr Mikhailovich Lyapunov (Russian: Алекса́ндр Миха́йлович Ляпуно́в , ] ; June 6 [O.S. May 25] 1857 – November 3, 1918) was a Russian mathematician, mechanician and physicist.
 His surname is sometimes romanized as Ljapunov, Liapunov, Liapounoff or Ljapunow.
 He was the son of astronomer Mikhail Lyapunov and the brother of pianist and composer Sergei Lyapunov.

Question: Who has one more Fields Medals, Vladimir Voevodsky or Aleksandr Lyapunov.?
Answer: Vladimir Alexandrovich Voevodsky