On instance definition for non-source sort -- philosophical discussion

[zhangyuanlin]

1. We need instance for non-source sorts in structure

Example 1 (monkey banana problem) 
            release :: actions
                attributes
                    releaser : agents
                    released_thing : things

We don't want to make release an instance of every leaf node of actions.

2. We use the alice-professor example to illustrate two different opinions

Theory
……
sorts declarations
    professor :: person
    assistant; associate; full :: professor
……
Structure
 alice in professor

2.1 Opinion 1 (from ALM paper)

The example has three pre-models: 
professor = {alice}, assistant = { alice }, associate = {}, full = {}.
professor = {alice}, assistant = {}, associate = { alice }, full = {}.
professor = {alice}, assistant = {}, associate = {}, full = { alice }.

2.2 Opinion 2

The example has only one pre-model
professor = {alice}, assistant = { alice }, associate = {}, full = {}.
professor = {alice}, assistant = {}, associate = { alice }, full = {}.
professor = {alice}, assistant = {}, associate = {}, full = { alice }.