Ideas in this flowchart

• Maximum cardinality of the relation between A and S
• The stated maximum cardinality is 6.
• This maximum is presented under the condition that all three athletes played all three sports.
• The relation is assumed to mean “plays.”
• Other possible meanings include “is a fan of” and “knows the rules for.”
• The maximum cardinality is said to remain 6 regardless of the relation’s precise meaning.