  Writing declarative models has numerous benefits, ranging from automated
reasoning and correction of design-level properties be-fore systems are built,
to automated testing and debugging of their implementations after they are
built. Alloy is a declarative modeling language that is well suited for
verifying system designs. A key strength of Alloy is its scenario-finding
toolset, the Analyzer, which allows users to explore all valid scenarios that
adhere to the model's constraints up to a user-provided scope. In Alloy, it is
common for users to desire to first validate smaller scenarios, then once
confident, move onto validating larger scenarios. However, the Analyzer only
presents scenarios in the order they are discovered by the SAT solver. This
paper presents Reach, an extension to the Analyzer which allows users to
explore scenarios by size. Experimental results reveal Reach's enumeration
improves performance while having the added benefit of maintaining a
semi-sorted ordering of scenarios for the user. Moreover, we highlight Reach's
ability to improve the performance of Alloy's analysis when the user makes
incremental changes to the scope of the enumeration.
