(1) Plain English
The declaration Dspatial sets the spatial dimension to the natural number 3.
(2) Importance in Recognition Science
It seeds the RS cardinality spectrum by serving as a primitive generator. For example, it produces eightTick = 2^Dspatial and gap45 = Dspatial² * Dconfig, yielding the structured list of canonical cardinalities rather than arbitrary numbers. The value 3 is required for non-trivial circle linking in the D-sphere.
(3) Reading the Formal Statement
def Dspatial : ℕ := 3 is a Lean definition introducing a constant Dspatial of type ℕ (natural numbers) whose value is definitionally equal to 3. This equality is immediately usable in by decide proofs and in dependent theorems.
(4) Dependencies and Certificates
It is a base generator in the module with no upstream dependencies shown. It is referenced in eightTick_eq, gap45_eq, and cubeFaces_eq. The full set of relations is packaged in the certificate cardinalitySpectrumCert, which includes the field Dspatial_is_3 : Dspatial = 3.
(5) What It Does Not Prove
The definition itself does not establish why the dimension equals 3; that equivalence is proved separately by alexander_duality_circle_linking. It also does not derive the full forcing chain or physical consequences beyond the listed spectrum decompositions.