Question: Which mathematician defined the Voronoi diagram, Mikhail Kravchuk or Georgy Voronoy?
Context: Mykhailo Pylypovych Kravchuk, also Krawtchouk (Ukrainian: Миха́йло Пили́пович Кравчу́к ) (September 27, 1892 – March 9, 1942), was a Soviet Ukrainian mathematician who, despite his early death, was the author of around 180 articles on mathematics. Fortune's algorithm is a sweep line algorithm for generating a Voronoi diagram from a set of points in a plane using O("n" log "n") time and O("n") space.  It was originally published by Steven Fortune in 1986 in his paper "A sweepline algorithm for Voronoi diagrams." Georgy Feodosevich Voronoy (Ukrainian: Георгій Феодосійович Вороний ; Russian: Гео́ргий Феодо́сьевич Вороно́й ; 28 April 1868 – 20 November 1908) was a Russian and Ukrainian mathematician.  Among other things, he defined the Voronoi diagram. In computational geometry, a power diagram is a partition of the Euclidean plane into polygonal cells defined from a set of circles, where the cell for a given circle "C" consists of all the points for which the power distance to "C" is smaller than the power distance to the other circles.  It is a form of generalized Voronoi diagram, and coincides with the Voronoi diagram of the circle centers in the case that all the circles have equal radii. In mathematics, a Voronoi formula is an equality involving Fourier coefficients of automorphic forms, with the coefficients twisted by additive characters on either side.  It can be regarded as a Poisson summation formula for non-abelian groups.  The Voronoi (summation) formula for GL(2) has long been a standard tool for studying analytic properties of automorphic forms and their "L"-functions.  There have been numerous results coming out the Voronoi formula on GL(2).  The concept is named after Georgy Voronoy. In mathematics, a weighted Voronoi diagram in "n" dimensions is a special case of a Voronoi diagram.  The Voronoi cells in a weighted Voronoi diagram are defined in terms of a distance function.  The distance function may specify the usual Euclidean distance, or may be some other, special distance function.  Usually, the distance function is a function of the generator points' weights. Ivan Ivanovich Ivanov (Russian: Иван Иванович Иванов ; 11 August 1862 – 17 December 1939) was a Russian-Soviet mathematician who worked in the field of number theory.  Together with Georgy Voronoy he continued Pafnuty Chebyshev's work on the subject. In geometry, the positive and negative Voronoi poles of a cell in a Voronoi diagram are certain vertices of the diagram. In mathematics, a Voronoi diagram is a partitioning of a plane into regions based on distance to points in a specific subset of the plane.  That set of points (called seeds, sites, or generators) is specified beforehand, and for each seed there is a corresponding region consisting of all points closer to that seed than to any other.  These regions are called Voronoi cells.  The Voronoi diagram of a set of points is dual to its Delaunay triangulation. In geometry, a centroidal Voronoi tessellation (CVT) is a special type of Voronoi tessellation or Voronoi diagram.  A Voronoi tessellation is called centroidal when the generating point of each Voronoi cell is also its mean (center of mass).  It can be viewed as an optimal partition corresponding to an optimal distribution of generators.  A number of algorithms can be used to generate centroidal Voronoi tessellations, including Lloyd's algorithm for K-means clustering.
Answer: Georgy Feodosevich Voronoy