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System-Theoretic Analysis of Dynamic Generalized Nash Equilibrium Problems -- Turnpikes and Dissipativity

Sophie Hall, Florian Dörfler, Timm Faulwasser

TL;DR

This work analyzes open-loop trajectories in finite-horizon dynamic generalized Nash equilibrium problems (GNEPs) from a system-theoretic lens, introducing dissipativity-based turnpike analysis to GNEPs. It proves that strict dissipativity with respect to the steady-state GNE $(x_s,u_s)$ induces a measure turnpike and, under a local minimality assumption, establishes a converse result. The authors define a game value function $V_N(x)$ whose gradient ties to the initial dual data and show how the storage function gradient relates to the steady-state multipliers, linking GNEP optimality to classical optimal-control concepts. They propose per-agent linear end penalties, including a learning scheme to adapt these penalties online, to suppress leaving arcs and ensure convergence to $(x_s,u_s)$ in open-loop trajectories. Numerical simulations on coupled GNEP examples validate turnpike behavior and demonstrate the effectiveness of linear penalties and penalty learning in enforcing steady-state operation.

Abstract

Generalized Nash equilibria are used in multi-agent control applications to model strategic interactions between agents that are coupled in the cost, dynamics, and constraints. We study the properties of open-loop GNE trajectories from a system-theoretic perspective. We show how strict dissipativity generates the turnpike phenomenon in GNE solutions. Moreover, we establish a converse turnpike result, i.e., the implication from turnpike to strict dissipativity. We derive conditions under which the steady-state GNE is the optimal operating point and, using a game value function, we give a local characterization of the geometry of storage functions. Finally, we design linear terminal penalties that ensure GNE open-loop trajectories converge to and remain at the steady-state GNE. These connections provide the foundation for future system-theoretic analysis of GNEs similar to those existing in optimal control.

System-Theoretic Analysis of Dynamic Generalized Nash Equilibrium Problems -- Turnpikes and Dissipativity

TL;DR

This work analyzes open-loop trajectories in finite-horizon dynamic generalized Nash equilibrium problems (GNEPs) from a system-theoretic lens, introducing dissipativity-based turnpike analysis to GNEPs. It proves that strict dissipativity with respect to the steady-state GNE induces a measure turnpike and, under a local minimality assumption, establishes a converse result. The authors define a game value function whose gradient ties to the initial dual data and show how the storage function gradient relates to the steady-state multipliers, linking GNEP optimality to classical optimal-control concepts. They propose per-agent linear end penalties, including a learning scheme to adapt these penalties online, to suppress leaving arcs and ensure convergence to in open-loop trajectories. Numerical simulations on coupled GNEP examples validate turnpike behavior and demonstrate the effectiveness of linear penalties and penalty learning in enforcing steady-state operation.

Abstract

Generalized Nash equilibria are used in multi-agent control applications to model strategic interactions between agents that are coupled in the cost, dynamics, and constraints. We study the properties of open-loop GNE trajectories from a system-theoretic perspective. We show how strict dissipativity generates the turnpike phenomenon in GNE solutions. Moreover, we establish a converse turnpike result, i.e., the implication from turnpike to strict dissipativity. We derive conditions under which the steady-state GNE is the optimal operating point and, using a game value function, we give a local characterization of the geometry of storage functions. Finally, we design linear terminal penalties that ensure GNE open-loop trajectories converge to and remain at the steady-state GNE. These connections provide the foundation for future system-theoretic analysis of GNEs similar to those existing in optimal control.
Paper Structure (13 sections, 1 theorem, 64 equations, 6 figures, 1 algorithm)

This paper contains 13 sections, 1 theorem, 64 equations, 6 figures, 1 algorithm.

Key Result

Proposition 1

Suppose the set $\mathcal{S}_{\infty}^{GNE}(\mathbf{x}) \not= \emptyset$, then if GNEP eq:MPCPerAgent is strictly dissipative with respect to $(x_s,u_s)$ following Definition dfn:StrictDiss, it is optimally operated at the steady-state GNE $(x_s,u_s)$ and suboptimally operated off steady state.

Figures (6)

  • Figure 1: Schematic of a state trajectory exhibiting the turnpike property for different horizon lengths.
  • Figure 2: Overview of implications between strict dissipativity, turnpike and optimal operation at the steady-state GNE.
  • Figure 3: Finite-horizon and steady-state GNEP with GNE-KKT system
  • Figure 4: Open-loop GNE trajectories of \ref{['eq:GNEP_example']} without terminal penalty.
  • Figure 5: Open-loop GNE trajectories of \ref{['eq:GNEP_example']} with a $\lambda_s\, x_N$ penalty.
  • ...and 1 more figures

Theorems & Definitions (11)

  • Definition 1: Generalized Nash equilibrium
  • Definition 2: Steady-state GNE
  • Remark 1: Existence & computation
  • Definition 3: Strict dissipativity of GNEPs
  • Remark 2: Why restrict dissipativity to $\mathcal{S}^{\text{\tiny GNE}}_N?$
  • Definition 4: Measure turnpike in GNEPs
  • Remark 3: Turnpike with strict $x$ dissipativity
  • Definition 5: $\varepsilon$-GNE chen2021distributed
  • Definition 6: Optimal operation of RHG
  • Proposition 1
  • ...and 1 more