Visualization in Comet
Comet features a declarative graphical layer to maintain visualizations incrementally during search. It also provides model-based visualizations, which are derived systematically from the model and are specified using a simple declarative language. 
A visualization of the objective function in a uncapacitated warehouse location on a difficult GAP instance.
Capacity constraints in car sequencing. Red entries show violations of a capacity constraint by a car on a slot of the assembly line
Violations of all cardinality constraints in the progressive party
Visualizing the nature of violations on the progressive party problem