Eliminating the unit constant in the Lambek calculus with brackets

We present a translation of the Lambek calculus with brackets and the unit constant, $\mathbf{Lb}^{{\boldsymbol{*}}_{\mathbf{1}}$,} into the Lambek calculus with brackets allowing empty antecedents, but without the unit constant, $\mathbf{Lb}^{{\boldsymbol{*}}$.} Using this translation, we extend previously known results for $\mathbf{Lb}^{{\boldsymbol{*}}$} to $\mathbf{Lb}^{{\boldsymbol{*}}_{\mathbf{1}}$:} (1) languages generated by categorial grammars based on the Lambek calculus with brackets are context-free (Kanazawa 2017); (2) the polynomial-time algorithm for deciding derivability of bounded depth sequents (Kanovich et al. 2017).