A Note on "A Simplified Account of Polymorphic References"

In the paper [1] a proof of the soundness of type inference for a functional language combining polymorphism and references is presented. The sense in which soundness is established merits further clarification, provided in this paper.

[1]  Matthias Felleisen,et al.  A Syntactic Approach to Type Soundness , 1994, Inf. Comput..

[2]  Robert Harper,et al.  A Simplified Account of Polymorphic References , 1994, Inf. Process. Lett..

[3]  Mads Tofte,et al.  Type Inference for Polymorphic References , 1990, Inf. Comput..

[4]  Robin Milner,et al.  A Theory of Type Polymorphism in Programming , 1978, J. Comput. Syst. Sci..

[5]  Per Martin-Löf,et al.  Intuitionistic type theory , 1984, Studies in proof theory.