On the Pre- and Post-Positional Semi-Random Graph Processes

Abstract

We study the semi-random graph process, and a variant process recently suggested by Nick Wormald. We show that these two processes are asymptotically equally fast in constructing a semi-random graph $G$ that has property $P$, for the following examples of $P$: (1) $P$ is the set of graphs containing a fixed $d$-degenerate subgraph, where $d\ge 1$ is fixed and (2) $P$ is the set of $k$-connected graphs, where $k\ge 1$ is fixed. In particular, our result of the $k$-connectedness above settles the open case $k=2$ of the original semi-random graph process. We also prove that there exist properties $P$ where the two semi-random graph processes do not construct a graph in $P$ asymptotically equally fast. We further propose some conjectures on $P$ for which the two processes perform differently.