230 space groups: the exact 230, 219, and 65 counts
OpenLeanEval.Geometry.SpaceGroupsProblem.space_groupsConsider all subgroups of the affine isometry group of satisfying the finite-displacement discreteness condition and containing translations by three linearly independent vectors, as specified in the accompanying definitions. Write for their number of classes under conjugation by affine maps of positive linear determinant, for the number under arbitrary invertible affine conjugacy, and for the number under the first relation after restricting to groups whose every isometry has positive linear determinant. Then the single goal is the conjunction
The third number counts the Sohncke subfamily. All three numbers are cardinalities in the extended natural numbers of sets of class subsets, so the equalities assert finiteness as well as exact values. This is the unchanged LeanEval benchmark assertion, not just the length of a list of named space groups.
Formalization Note. The imported definition bundle preserves the source declarations verbatim. The declaration is an unproved statement placeholder, not a submitted proof. It is the sole theorem item; there are no milestones or auxiliary theorem items.
import Mathlib import Definitions.Def_LeanEval_SpaceGroups_Definitions
namespace LeanEval
namespace Geometry
namespace SpaceGroupsProblem
theorem space_groups :
crystallographicCountOP 3 = 230 ∧
crystallographicCount 3 = 219 ∧
crystallographicCountOPOnly 3 = 65 := by
sorry
end SpaceGroupsProblem
end Geometry
end LeanEval
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What the Lean code literally says, in plain math · gpt-6-astra
In Euclidean space , let be the collection of subgroups of the group of bijective affine isometries satisfying both of these conditions: for every and every real , the set is finite; and there exist three linearly independent vectors such that, for each , some satisfies for every . For , write when there exists an invertible affine map such that , viewing both sides as sets of affine maps, and write when such a can be chosen with strictly positive determinant of its linear part. Let consist of those for which every has strictly positive determinant of its linear part. The theorem asserts simultaneously that the collection of distinct subsets has cardinality , the collection has cardinality , and the collection has cardinality , where each cardinality is taken in the extended natural numbers, with every infinite set assigned cardinality .
Confirmed by the mission captain (proposal self-audit).