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Not -.  0 _ _ Less

-.y is 1-y ; for a boolean argument it is the complement (not); for a probability, it is the complementary probability.
 
  x-.y includes all items of x except for those that are cells of y .

Tolerance t is provided by -.!.t .
 

The function less applies to any conformable pair of arguments. For example:
   (i. 9) -. 2 3 5 7
0 1 4 6 8
                
   'abcdefghij' -. 'aeiou'
bcdfghj

   ]m=: i. 4 5 
 0  1  2  3  4
 5  6  7  8  9
10 11 12 13 14
15 16 17 18 19

   m -. 5 6 7 8 9
 0  1  2  3  4
10 11 12 13 14
15 16 17 18 19
 
   b=: <\ 'abcdefg'
   b
+-+--+---+----+-----+------+-------+
|a|ab|abc|abcd|abcde|abcdef|abcdefg|
+-+--+---+----+-----+------+-------+

   b -. 'abc';'abcde';'cba'
+-+--+----+------+-------+
|a|ab|abcd|abcdef|abcdefg|
+-+--+----+------+-------+

   2 3 4 5 -. 'abcdef'
2 3 4 5



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