TY - GEN
T1 - Equivalence and Separation Between Heard-Of and Asynchronous Message-Passing Models
AU - Attiya, Hagit
AU - Castañeda, Armando
AU - Ghosh, Dhrubajyoti
AU - Nowak, Thomas
N1 - Publisher Copyright: © The Author(s), under exclusive license to Springer Nature Switzerland AG 2026.
PY - 2026
Y1 - 2026
N2 - We revisit the relationship between two fundamental models of distributed computation: the asynchronous message-passing model with up to f crash failures (AMPf) and the Heard-Of model with up to f message omissions (HOf). We show that for n>2f, the two models are equivalent with respect to the solvability of colorless tasks, and that for colored tasks the equivalence holds only when f=1 (and n>2). The separation for larger f arises from the presence of silenced processes in HOf, which may lead to incompatible decisions. The results are proved through bidirectional simulations between AMPf and HOf, using an intermediate model that captures this notion of silencing. The results extend to randomized protocols against a non-adaptive adversary, indicating that the expressive limits of canonical rounds are structural rather than probabilistic. Together, these results help to delineate where round-based abstractions capture asynchronous computation, and where they do not.
AB - We revisit the relationship between two fundamental models of distributed computation: the asynchronous message-passing model with up to f crash failures (AMPf) and the Heard-Of model with up to f message omissions (HOf). We show that for n>2f, the two models are equivalent with respect to the solvability of colorless tasks, and that for colored tasks the equivalence holds only when f=1 (and n>2). The separation for larger f arises from the presence of silenced processes in HOf, which may lead to incompatible decisions. The results are proved through bidirectional simulations between AMPf and HOf, using an intermediate model that captures this notion of silencing. The results extend to randomized protocols against a non-adaptive adversary, indicating that the expressive limits of canonical rounds are structural rather than probabilistic. Together, these results help to delineate where round-based abstractions capture asynchronous computation, and where they do not.
KW - Asynchronous message-passing model
KW - Equivalence of models
KW - Heard-Of model
KW - Message adversaries
KW - Task solvability
UR - https://www.scopus.com/pages/publications/105040971533
U2 - 10.1007/978-3-032-26465-7_4
DO - 10.1007/978-3-032-26465-7_4
M3 - Conference contribution
SN - 9783032264640
T3 - Lecture Notes in Computer Science
SP - 53
EP - 72
BT - Structural Information and Communication Complexity - 33rd International Colloquium, SIROCCO 2026, Proceedings
A2 - Georgiou, Chryssis
PB - Springer Science and Business Media Deutschland GmbH
T2 - 33rd International Colloquium on Structural Information and Communication Complexity, SIROCCO 2026
Y2 - 9 June 2026 through 11 June 2026
ER -