AbstractThis article provides new insight into the connection between the trace-based lower part of van Glabbeek’s linear-time, branching-time spectrum and its simulation-based upper part. We establish that ready simulation is fully abstract with respect to failure inclusion, when adding the conjunction operator that was proposed by the authors in [TCS 373 (1–2) 19–40] to the standard setting of labelled transition systems with (CSP-style) parallel composition. More precisely, we actually prove a stronger result by considering a coarser relation than failure inclusion, namely a preorder that relates processes with respect to inconsistencies that may arise under conjunctive composition.Ready simulation is also shown to satisfy standard logic...