x1 is any child of the first child of the first child of ... the first child of x2, where the graph geodesic through the ancestorship-directed family tree from x1 to x2 is of length (x3) + 1 (li; x3 must be a nonnegative integer or positive infinity), and where "first" is according to (partial) ordering rule x4 (default: chronological order of birth per successive generation within the given lineage; other restrictions on legitimacy etc. may be specified here as well).
x1 is any child of the first child of the first child of ... the first child of x2, with intermediate steps x3 (complete ordered list, "ce'o"; should include the relevant parent of x1), where "first" is according to (partial) ordering rule x4 (default: chronological order of birth per successive generation within the given lineage; other restrictions on legitimacy etc. may be specified here as well).
x1 [mass of properties describing skills, technological advances] is a civilization of x2 (mass of persons) manifesting Type x3 (number) on the Kardashev scale of technological advancement according to standard/particular scale/definition x4.