Content-Oblivious Leader Election in 2-Edge-Connected Networks

Abstract: Censor-Hillel, Cohen, Gelles, and Sela (PODC 2022 & Distributed Computing 2023) studied fully-defective asynchronous networks, where communication channels may suffer an extreme form of alteration errors, rendering messages completely corrupted. The model is equivalent to content-oblivious computation, where nodes communicate solely via pulses. They showed that if the network is 2-edge-connected, then any algorithm for a noiseless setting can be simulated in the fully-defective setting; otherwise, no non-trivial computation is possible in the fully-defective setting. However, their simulation requires a predesignated leader, which they conjectured to be necessary for any non-trivial content-oblivious task. Recently, Frei, Gelles, Ghazy, and Nolin (DISC 2024) refuted this conjecture for the special case of oriented ring topology. They designed two asynchronous content-oblivious leader election algorithms with message complexity $O(n \cdot \mathsf{ID}{\max})$, where $n$ is the number of nodes and $\mathsf{ID}{\max}$ is the maximum $\mathsf{ID}$. The first algorithm stabilizes in unoriented rings without termination detection. The second algorithm quiescently terminates in oriented rings, thus enabling the execution of the simulation algorithm after leader election. In this work, we present an asynchronous content-oblivious leader election algorithm that quiescently terminates in any 2-edge connected network with message complexity $O(m \cdot N \cdot \mathsf{ID}{\min})$, where $m$ is the number of edges, $N$ is a known upper bound on the number of nodes, and $\mathsf{ID}{\min}$ is the smallest $\mathsf{ID}$. Combined with the previous simulation result, our finding implies that any algorithm from the noiseless setting can be simulated in the fully-defective setting without assuming a preselected leader, entirely refuting the original conjecture.