Type Promotion

Conventional Approach

• For each symbol f
• with argument types T_i interpreted in D_i
• define f' with argument types D_i
• Interpret f using f'

Avoiding f'

• For each symbol f
• Interpret f with argument types D_i
• Not well typed

Type Promotion

• For each problem type T interpreted in the domain D
• define "type promotion" bijections D2T, D → T
• Interpret f with argument types D2T(D_i)
• The D2T are never "evaluated"