  This paper defines a sound and complete semantic criterion, based on
reducibility candidates, for strong normalization of theories expressed in
minimal deduction modulo \`a la Curry. The use of Curry-style proof-terms
allows to build this criterion on the classic notion of pre-Heyting algebras
and makes that criterion concern all theories expressed in minimal deduction
modulo. Compared to using Church-style proof-terms, this method provides both a
simpler definition of the criterion and a simpler proof of its completeness.
