It’s sometimes inconvenient, especially if we want to focus on the parallel structure of a computation, for a vertex of a trace to represent only one executed instruction. Consequently, if a chain of instructions contains no parallel or procedural control (no cilk_spawn, cilk_sync, procedure call, or return—via either an explicit return statement or the return that happens implicitly upon reaching the end of a procedure), we group the entire chain into a single strand. Strands do not include instructions that involve parallel or procedural control. These control dependencies must be represented as edges in the trace.