Paola Valdivia, Paolo Buono, Catherine Plaisant, Nicole Dufournaud and Jean-Daniel Fekete

Time and Place: Friday, 02.07., 14:00–14:20, Room 1
Session: Software Demos

Keywords: dynamic graph; dynamic hypergraphs; digital humanities; case study; interaction

We present PAOHVis, an interactive tool that uses the Parallel Aggregated Ordered Hypergraph (PAOH) representation. PAOH is a visualization of networks that are modeled as dynamic hypergraphs. A large category of datasets in social history can be represented as dynamic hypergraphs, for example, people that are connected through dated documents, such as contracts, but also marriage certificates, and justice decisions. In that case, people are represented as nodes and each document is a hyperedge that connects all people mentioned in it.

PAOH encodes nodes as parallel horizontal bars, optionally colored to represent an attribute of the node. Node labels are placed on the left side of the display. Hyperedges are parallel vertical lines connecting the nodes, with the connections emphasized with a dot. PAOH represents time flowing from left to right as a series of time slots separated by small white gaps. Each time slot corresponds to an interval of time. In PAOHVis we have implemented some standard interactive functionalities, like highlighting, selecting, filtering, and group and time aggregation to facilitate the analysis.

Let’s see how PAOHVis was used by a historian studying a collection of contracts describing trade relations in the 17th century in Nantes, France. She was interested in analyzing the role of a non-married merchant woman, Marie Boucher. Our collaborator wanted to understand the relationships that Boucher had with other merchants over time. The Boucher dataset is composed of 59 contracts mentioning 90 persons. Each person is modeled as a node, and the color of the background represents their family. Each contract is modeled as a hyperedge linking several persons. Each contract has a signature date.

Our collaborator found the PAOH representation clear. Using PAOHVis she found that in 1667 Marie Boucher had two contracts with Jean Boucher and two with Seigneur de Nays — in the past she had assumed that two persons connected during the same year appeared in only one contract. Our collaborator also explained that three main phases had been identified after the lengthy prior analysis: an initial phase from 1660 to 1664 with mostly French trading, a second phase with cross Atlantic trade from 1666 to 1668, and a third expansion phase until 1675, after which Marie disappears from the records until a 1689 document mention of her being deceased. Those phases were apparent in PAOHVis. She commented that it provided good narrative support, and would be useful to communicate the findings. Also, the color-coding was found useful to represent the strong —and changing— family connections.

PAOH is the first technique to provide a highly readable representation of dynamic hypergraphs. It is easy to learn and well suited for medium size dynamic hypergraphs (50-500 nodes). Our interactive tool, PAOHVis, helps users to perform detailed analysis, and using the aggregation functionalities, the relations between groups become evident and larger datasets can be analyzed. PAOHVis is released under the BSD 3-Clause License. Details on how to use PAOHVis and a link to an online demo can be found at https://www.aviz.fr/paohvis.