The discretionary of the word `difficult’

discretionarytex-core

Is the discretionary of the word difficult di\discretionary{f-}{fi}{ffi}cult equivalent to dif\-ficult (or dif\discretionary{-}{}{})?

Best Answer

The TeXbook, p. 95

The most common case of a discretionary break is a simple discretionary hyphen

\discretionary{-}{}{}

for which TeX accepts the abbreviation \-.

Hence dif\-ficult is equivalent to dif\discretionary{-}{}{}ficult.

You can also see this in the output log:

\showboxbreadth=\maxdimen
\showboxdepth=\maxdimen
\setbox0\hbox{dif\-ficult}
\showbox0
\bye

> \box0=
\hbox(6.94444+0.0)x33.6112
.\tenrm d
.\tenrm i
.\tenrm f
.\discretionary
..\tenrm -
.\tenrm ^^L (ligature fi)
.\tenrm c
.\tenrm u
.\tenrm l
.\tenrm t

The other variant with di\discretionary{f-}{fi}{ffi}cult produces

> \box0=
\hbox(6.94444+0.0)x33.33342
.\tenrm d
.\tenrm i
.\discretionary replacing 1
..\tenrm f
..\tenrm -
.|\tenrm ^^L (ligature fi)
.\tenrm ^^N (ligature ffi)
.\tenrm c
.\tenrm u
.\tenrm l
.\tenrm t
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