Parigot鈥檚 -calculus (Parigot, 1992聽) is now a standard reference about the computational content of classical logic as well as for the formal study of control operators in functional languages. In addition to the fine-grained Curry-Howard correspondence between minimal classical deductions and simply typed -terms and to the ability to encode many usual control operators such as
call/cc in the -calculus (in its historical call-by-name presentation or in call-by-value versions), the success of the-calculus comes from its simplicity, its good meta-theoretical properties both as a typed and an untyped calculus (confluence, strong normalization,
etc.) as well as the fact that it naturally extends Church鈥檚 -calculus. Though, in 2001, David and Py proved聽 that B枚
hm鈥檚 theorem, which is a fundamental result of the untyped -calculus, cannot be lifted to Parigot鈥檚 calculus.
In the present article, we exhibit a natural extension to Parigot鈥檚 calculus, the-calculus, in which B枚hm鈥檚 property, also known as separation property, can be stated and proved. This is made possible by a careful and detailed analysis of David and Py鈥檚 proof of non-separability and of the characteristics of the -calculus which break the property: we identify that the crucial point lies in the design of Parigot鈥檚 -calculus with a two-level syntax. In addition, we establish a standardization theorem for the extended calculus, deduce a characterization of solvability, describe -B枚hm trees and connect the calculus with stream computing and delimited control.