Sigma Query in Time & Space

o

To find associations of two objects 'a' and 'b' from the 3 time slices of a hypermapped virtual world R the formal query is:
Sx (x1o, x2o) (St (t1, t2, t3) R)
In SigmaQL language:

SELECT     x
CLUSTER    OPEN x1, OPEN x2
FROM  SELECT     t
      CLUSTER    t1, t2, t3
      FROM       R