x y is by default interpreted as DoubleLeftTee[x, y].
x y z groups as (x y) z.
Used in mathematics to indicate various strong forms of logical implication of x from y—often tautological implication.
See The Mathematica Book: Section 3.10.4 and Section 3.10.4.
See also: \[LeftTee] , \[DoubleRightTee] .