Propositions, which are at the heart of Logic (OBC Topic 6), are statements that express a concept that can be true (a 'fact') or false (a 'fiction'; an 'illusion'; a 'lie'). Statements are a fundamental construct in OBC (Topic 8). In Logic 'objects', 'classes of objects', 'terms', and 'symbols' are what the propositions are 'about' and are therefore the key point where Logic contributes to 'concept' (OBC Topic 1). Mathematics intersects with Logic in Set Theory, Category Theory, and the Abstract Theory of Classes and Relations. The most specific mathematic connection with 'concept' is the Set Theory 'element' (OBC Topic 1), Category Theory 'category' (OBC Topic 3) and Abstract Theory 'class' and 'relations' (OBC Topic 4).