Documentation for infix ⊈ assembled from the following types:

language documentation Sets, bags, and mixes

From Sets, bags, and mixes

(Sets, bags, and mixes) infix ⊈

Returns True if $a is not a subset nor equal to $b, else False. More information, Wikipedia definition.

language documentation Operators

From Operators

(Operators) infix ⊈

multi sub infix:<⊈>($a,$b --> Bool:D)

Not a subset of nor equal to operator.

Returns True if $a is not a subset of $b. Equivalent to !(<=).

say (1,2,3) ⊄ (2,3,1); # OUTPUT: «True␤» 
say (2,3) ⊄ (2,3,1); # OUTPUT: «False␤» 
say 4 !(<=) (1,2,3); # OUTPUT: «True␤» 

⊈ is codepoint U+2288 (NEITHER A SUBSET OF NOR EQUAL TO).