“…We adopted the guideline that only proof-expression could suffer a change in the proof-theoretical format, but other, more "uniform", possibilities exist, where also the domain assignment relation is changed to the sequent calculus format. An improvement, in view of proof-search, is to restrict the conversion rule of the typing system to an expansion rule [36]. Finally, in λHJ mse , λωJ mse , and λ2J mse we re-encounter explicit substitutions in higher-order type theories [4,28], but with a simpler treatment (no explicit execution) and in a simpler setting (no dependent types).…”