What Can You Say About A Logic Sentence?

1. Are they strings?

"p and q" is 7 characters long.

2a. Are they lists of identifiers?

['p, 'and, 'q] is 3 identifiers long, and the first identifier is a constant (with an interpretation which is irrelevant to inference).

2b. Are they lists of things?

[p, and, q] is a list of three things; the first thing is ... something.

3a. Are they relationships between identifiers?

{ a Conjunction; left: 'p; right: 'q } is a conjunction object, with two operands; the left operand is a logic constant.

3b. Are they relationships between things?

{ a Conjunction; left: p; right q } is a conjunction object, with two operands; the left operand is a logic constant.

Down this road, 3a seems good (especially when we get to quantifiers, where an operand is a logic-variable, instead of a logic-constant).

Between 2a and 3a, where you just separate out the predicate (operator) from the rest (operands) is an especially nice place. We'll come back to this in designing an ontology, on slide 18 (RDF Layering).