Both \[ \leq \simeq \leq \sim \leq \]
and \[ \leq \simeq \leq_A \sim \leq_B \]
lead to similar results when it comes to spacing as all of the symbols are treated as relations.
Putting curly braces around \leq_A
, so it becomes {\leq_A}
, results in {\leq_A}
switching its type from mathrel
to mathord
(see What is the difference between \mathbin vs. \mathrel?); so LaTeX treats {\leq_A} \sim {\leq_B}
as any ordinary symbol just like a \sim b
.
What to do really depends on the meaning of your input.
If you want to establish a binary relation between \leq_A
and \leq_B
with \sim
(let's say: equivalence of two binary relations) just like a relation between a
and b
, you need to wrap \leq_A
and \leq_B
in curly braces or \mathord
, define a new command for that if you need it more often.
If you want \leq \simeq \leq_A \sim \leq_B
to act like one massive relation, just leave it as it is.
$4-5\quad \times-3$
.\leq
, inside curly brackets, then does LaTeX treat the\sim
as being between two non-relation symbols and thus restore the padding?\newcommand{\oleq}{\mathord{\leq}}
.