Analogy with linguistic levels

Three levels of abstraction (e.g. HPSG, ILEX):

Integrated language-extension model:

     -  L_s - A_s  (semantic interpretation)
   /
  S 
   \
     -  L_p  - A_p (phonetic interpretation)
     -  L_t  - A_t (textual interpretation)

• Semantic interpretation:

  : Logical Form

  : Semantic Model (extensional domain)

• Phonetic interpretation

  : Phonological Form

  : Phonetic Model (speech signal domain)

• By analogy: textual interpretation:

  : Textual Form

  : Textual Model (visual token domain)

Extensional / signal / token domain:

empirical observables/measurables, down to the pixel/sample level