Booleans:
b⍳0
and
b⍳1
Index
<<
>>
b⍳0 b⍳1
780
(b⍳1)↓x
v
(∨\b)/x
(b⍳0)↑x
v
(∧\b)/x
∧\b ←→ (⍳n)<b⍳0
0 at or after the first 0
∨\b ←→ (⍳n)≥b⍳1
1 at or after the first 1
<\b ←→ (⍳n)=b⍳1
0 after the first 1