Studies of Euler diagrams/filtrates

dummy To filtrate a Boolean function means to reduce its information about many sets to those of interest.
Graphically it means removing circles from the Euler diagram and treating all merged cells as true, if any of the component cells are true.

medusa

original ABCD
The 4 sets create 13 cells.

BCD (A removed)
The result is a 3-circle Venn diagram without gapspots, i.e. the tautology.

ABD (C removed)
The result shows all intersections except that of all three circles. (The usual representation would be a Venn diagram with a gapspot in the middle. See bunese.)

doguva

This is a gap variant of bazinga. The 8 sets create 18 true cells and 3 gaps.
Both B and C border all the three gapspots. Removing them merges the gapspots with their full neighbors.

ACDEFGH (B removed)
original	13 cells

ABDEFGH (C removed)
original	13 cells

ABDEFH (CG removed)
original	10 cells

ACDGH (BEF removed)
original	9 cells

The following filtrates leave a single gapspot.

ABCDGH (EF removed)
original	14 true cells + 1 gap

BCDEFH (AG removed)
original	13 true cells + 1 gap

tomute

Also a gap variant of bazinga. The 8 sets create 10 true cells and 8 gaps.

ABCD (EFGH removed)       vanatu
original	7 true cells + 5 gaps

BCDE (AFGH removed)       darimi
original	7 true cells + 2 or 3 gaps

barita

The 6 sets create 21 cells.

ABC (DEF removed)        tautology
(The remaining circles vanish.)

ACDF (BE removed)        seduki   (like putuki)
9 cells

BCDEF (A removed)        sedofu   (like gepofu)
9 cells    (D vanishes)

ACDEF (B removed)        sediri   (like miniri)
15 cells