/usr/share/X11/locale/en_US.UTF-8/Compose
(Ubuntu 18.04) defines compose sequences for accented variations of the turned "e" character:
<dead_acute> <U018E> : "Ǝ́" # LATIN CAPITAL LETTER TURNED E WITH ACUTE
<dead_grave> <U018E> : "Ǝ̀" # LATIN CAPITAL LETTER TURNED E WITH GRAVE
<dead_circumflex> <U018E> : "Ǝ̂" # LATIN CAPITAL LETTER TURNED E WITH CIRCUMFLEX
<dead_caron> <U018E> : "Ǝ̌" # LATIN CAPITAL LETTER TURNED E WITH CARON
<dead_macron> <U018E> : "Ǝ̄" # LATIN CAPITAL LETTER TURNED E WITH MACRON
<dead_tilde> <U018E> : "Ǝ̃" # LATIN CAPITAL LETTER TURNED E WITH TILDE
<dead_acute> <dead_tilde> <U018E> : "Ǝ̃́" # LATIN CAPITAL LETTER TURNED E WITH TILDE AND ACUTE
<dead_grave> <dead_tilde> <U018E> : "Ǝ̃̀" # LATIN CAPITAL LETTER TURNED E WITH TILDE AND GRAVE
<dead_acute> <U01DD> : "ǝ́" # LATIN SMALL LETTER TURNED E WITH ACUTE
<dead_grave> <U01DD> : "ǝ̀" # LATIN SMALL LETTER TURNED E WITH GRAVE
<dead_circumflex> <U01DD> : "ǝ̂" # LATIN SMALL LETTER TURNED E WITH CIRCUMFLEX
<dead_caron> <U01DD> : "ǝ̌" # LATIN SMALL LETTER TURNED E WITH CARON
<dead_macron> <U01DD> : "ǝ̄" # LATIN SMALL LETTER TURNED E WITH MACRON
<dead_tilde> <U01DD> : "ǝ̃" # LATIN SMALL LETTER TURNED E WITH TILDE
<dead_acute> <dead_tilde> <U01DD> : "ǝ̃́" # LATIN SMALL LETTER TURNED E WITH TILDE AND ACUTE
<dead_grave> <dead_tilde> <U01DD> : "ǝ̃̀" # LATIN SMALL LETTER TURNED E WITH TILDE AND GRAVE
but strangely, it doesn't define a sequence for the character itself.
It doesn't even define the similar characters (U+2203 ∃ "there exists") and (U+0259 ə "schwa").
Is there some sequence for these characters (Ǝ U+018E, and ǝ U+01DD), or do I have to define it myself in my ~/.XCompose file?
And if not, why aren't they defined along with the accented versions?
ə
is defined as multi_key+e+e on my system (Debian Buster). Another 5 releases from now, and you will have the whole set ;-)shift-ctrl-u 18e<enter>
work for you? Repeating e generates an ə in compose.