Adjusting kerning for different preceding characters

Questions
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4

I think the cause of the spacing is that "..."creates a space-sensitive frame: spacing is added when there is a space in the source code. See here and here.

This means you can “solve” the issue by removing the space after the dot:

#let V = $bold("Void")$

$
  Delta .#V tack gamma .#V : Gamma .#V \
  Gamma tack b : #V
$

image

Or using @ensko’s suggestion you could define #let pt(a, b) = $#a.#b$.