Would learned, describing how much knowledge a person has acquired, be treated as an ADJ or a VERB?

[AngledLuffa]

Came up as a possibility for models to tag learned as ADJ in some contexts

stanfordnlp/stanza#1319 (comment)

Such as, for example, "Oh Papa Homer, you are so learned"

I found some examples where trained in a similar context is a VERB:

stanfordnlp/stanza#1319 (comment)

there are also a couple rare examples in EWT where trained is an ADJ, usually after an AUX:

# sent_id = weblog-blogspot.com_healingiraq_20040409053012_ENG_20040409_053012-0009
11      and     and     CCONJ   CC      _       14      cc      14:cc   _
12      those   that    PRON    DT      Number=Plur|PronType=Dem        14      nsubj   14:nsubj|16:nsubj       _
13      are     be      AUX     VBP     Mood=Ind|Number=Plur|Person=3|Tense=Pres|VerbForm=Fin   14      cop     14:cop  _
14      trained trained ADJ     JJ      Degree=Pos      7       conj    7:conj:and      _
15      and     and     CCONJ   CC      _       16      cc      16:cc   _
16      armed   armed   ADJ     JJ      Degree=Pos      14      conj    14:conj:and     SpaceAfter=No

# sent_id = reviews-186284-0005
# text = She is so talented, the flowers were arranged superbly and delicately, it is so obvious to see the difference between someone fully trained and skilled compared to others.
24      fully   fully   ADV     RB      _       25      advmod  25:advmod       _
25      trained trained ADJ     JJ      Degree=Pos      23      amod    23:amod _
26      and     and     CCONJ   CC      _       27      cc      27:cc   _
27      skilled skilled ADJ     JJ      Degree=Pos      25      conj    23:amod|25:conj:and     _
28      compared        compare VERB    VBN     Tense=Past|VerbForm=Part|Voice=Pass     25      advcl   25:advcl        _
29      to      to      ADP     IN      _       30      case    30:case _
30      others  other   NOUN    NNS     Number=Plur     28      obl     28:obl:to       SpaceAfter=No

Suggestions?

[nschneid]

See e.g. UniversalDependencies/UD_English-EWT#480 regarding "united" and the criteria used in GUM to distinguish adjectives and participles.

I would say ADJ is correct for "learnèd" (it can't take a by-phrase, for example).

[amir-zeldes]

Agreed, even the stress pattern is not really compatible with regarding it as a participle, and it has idiosyncratic meaning.