Alphabet
 A B Ç D E Ä F G H I J Ž K L M N Ň O Ö P R S Ş T U Ü W Y Ý Z
 a b ç d e ä f g h i j ž k l m n ň o ö p r s ş t u ü w y ý z
 %{A%}:a %>:0  ;

Sets

Vowel = A E Ä I O Ö U Ü Y Ý 
        a e ä i o ö u ü y ý ;

Rules 

"Remove suffix vowel with vowel-ending stem"
i:0 <=> Vow %{VSUF%}:0 _ [ m | n ] ;

! Resources:
! https://wiki.apertium.org/wiki/Starting_a_new_language_with_HFST#Enter_twol
! https://kitwiki.csc.fi/twiki/bin/view/KitWiki/HfstHome
! https://github.com/hfst/
! https://wiki.apertium.org/wiki/Twol
! https://wiki.apertium.org/wiki/Hfst