TY - INPR A1 - Grimm, Veronika A1 - Grübel, Julia A1 - Schmidt, Martin A1 - Schwartz, Alexandra A1 - Wiertz, Ann-Kathrin A1 - Zöttl, Gregor T1 - On a Tractable Single-Level Reformulation of a Multilevel Model of the European Entry-Exit Gas Market with Market Power N2 - We propose a framework that allows to quantitatively analyze the interplay of the different agents involved in gas trade and transport in the context of the European entry-exit system. While previous contributions focus on the case of perfectly competitive buyers and sellers of gas, our novel framework considers the mathematically more challenging case of a strategic and monopolistic gas seller. We present a multilevel framework that is suitable to capture the sequential nature of the decisions taken. We then derive sufficient conditions that allow for reformulating the challenging four-level model as a computationally tractable single-level reformulation. We prove the correctness of this reformulation and use it for solving several test instances to illustrate the applicability of our approach. KW - Multilevel optimization KW - Reformulations KW - Gas markets KW - Market power Y1 - 2023 ER -