ABSTRACT
The locations of restriction sites can be determined in several ways. The essential tool is the capability of digesting DNA with one or more restriction enzymes along with the capability of measuring the resulting DNA fragments by gel electrophoresis. Maps are not usually determined by direct experimental data on overlaps Ai ⋂ Bj;, due to the difficulty of performing the experiments. Instead, the two single and one double digests are done, and the three batches of DNA are run in three lanes of a gel. This chapter describes the problem and proves a theorem regarding the nonuniqueness of solutions to the problem of determining restriction maps from these data. It introduces cassette transformations that define an equivalence relation on restriction maps. Each member of an equivalence class solves the same DDP=DDP. The correspondence between restriction maps, the border block graph and alternating Eulerian paths characterizes equivalence classes defined by these cassette transformations.
