# System F-sub

In the branch of mathematical logic known as type theory, System F<:, pronounced "F-sub", is an extension of system F with subtyping. System F<: has been of central importance to programming language theory since the 1980s[citation needed] because the core of functional programming languages, like those in the ML family, support both parametric polymorphism and record subtyping, which can be expressed in System F<:.

## References

• Cardelli, Luca; Martini, Simone; Mitchell, John C.; Scedrov, Andre (1994). "An extension of system F with subtyping". Information and Computation, vol. 9. North Holland, Amsterdam. pp. 4–56.
• Pierce, Benjamin (2002). Types and Programming Languages. MIT Press. ISBN 0-262-16209-1., Chapter 26: Bounded quantification