Teodor Sigaev <teodor@sigaev.ru> writes:
>> Why does the phrase distance operator assume <1> means adjacent words,
>> and not <0>. (FYI, <-> is the same as <1>.)
> Because
> 1 it is a result of subtruction of word's positions
> 2 <0> could be used as special case like a word with two infinitives:
This is actually documented, in 12.1.2:
A special case that's sometimes useful is that <0> can be used torequire that two patterns match the same word.
regards, tom lane