A presentation engine presents facts in a UI having a graph. Through manipulation of the UI, an end-user can add or remove facts from the graph, and can sort the facts shown in the graph based on values that are shown, or not shown, in the graph. The presentation engine determines a graph type that best facilitates interpretation of the facts by the end-user and automatically creates a graph of that type. Possible graph types include bar graphs, scatter plots, timelines, and maps.