# Ittai Abraham et al. - Partial Synchrony Variants (Highlights)  ## Highlights - **Bounded Partial Synchrony (BPS)**: A message sent at time tt arrives by time at most maxt,GST+Δmaxt,GST+Δ ([View Highlight](https://read.readwise.io/read/01kj4992jmf7zka09qbwyevde5)) ^990825601 This definition implicitly assumes that messages sent before GST are delayed but not lost, and that they all arrive by time GST+Δ. - **Unbounded Partial Synchrony (UPS)**: A message sent at time t≥GSTt≥GST arrives at time at most t+Δt+Δ. Other messages may have unbounded delay. ([View Highlight](https://read.readwise.io/read/01kj49bqd8w4wvrc6ge2jzqgt1)) ^990825660 UPS allows messages sent before GST to have unbounded delay - **Lossy Partial Synchrony (LPS)**: A message sent at time t≥GSTt≥GST arrives at time at most t+Δt+Δ. Other messages may have unbounded delay or may be dropped. ([View Highlight](https://read.readwise.io/read/01kj49c1s2ge113m90tkveb8c4)) ^990825666 LPS models systems where the network before GST is so unreliable that messages may be lost.