OF LOGICAL CLASS-FREQUENCIES, ETC. 
The planes representing conditions of inferior congruence are 
123 
X = 0 y z=i 0 z = () 
X = OT y = OT z = OT. 
The conditions of superior congruence are represented Ijy planes 
X y z — 0-1 (a) 
X y — z = X — y + z ■= — X y z = 0-2 y, 8) 
X + y z = 0-2 (e) 
X y — z = X — y z = — X y z ■= — 0-1 {'C, y, 0), 
but on drawing the figure (fig. 11) it will Ije seen that the planes (/S, y, S, y, 0) do 
not come into account, the surface being an octahedron bounded by (a) (e) and the six 
planes representing conditions of inferior congruence. 
There are no infinite series of definite Inferences but only six s|)ecial cases, 
corresponding to the points ABCDEF. They are all of the form 
or 
Given. Inferred. 
X — Q '?/ = ()] 
. . 1 2 — ()•: 
.r — OT y = Oil 
R 2 
