The problems of Interval Sandwich (IS)and Intervalizing Colored Graphs' (IC
G) have received a lot of attention recently, due to their applicability to
DNA physical mapping problems with ambiguous data. Most of the results obt
ained so far on the problems were hardness results. Here we study the probl
ems under assumptions of sparseness, which hold in the biological context.
We prove that both problems are polynomial when either (1) the input graph
degree and the solution graph clique size are bounded, or (2) the solution
graph degree is bounded. In particular, this implies that ICC is polynomial
on bounded degree graphs for every fixed number of colors, in contrast wit
h the recent result of Bodlaender and de Fluiter.