Phylogeny

Multiple parents can be adressed with the following syntax, where a and b are c's parents:

http://gexf.net/data/phylogeny.gexf
<?xml version="1.0" encoding="UTF-8"?>
<gexf xmlns="http://www.gexf.net/1.2" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.gexf.net/1.1 http://www.gexf.net/1.2/gexf.xsd" version="1.2">
    <graph>
        <nodes>
            <node id="a" label="cheese"/>
            <node id="b" label="cherry"/>
            <node id="c" label="cake">
                <parents>
                    <parent for="a"/>
                    <parent for="b"/>
                </parents>
            </node>
        </nodes>
    </graph>
</gexf>

See how to create beautiful graphs in the next example.