Questions about the Cross and Change operator

[Siyi-H]

Is there a precise mathematical theory about the Cross and Change operators. The Form and Diss operators are consistent with the paper which proposed STERGM. However, my understanding of the Cross and Change operators is not clear. Is the Change operator consistent with the paper which proposed TERGM? So what exactly does the cross operator represent?

[krivit]

That particular formulation goes back to Hanneke and Xing (2007), Hanneke, Fu, and Xing (2010), and Krackhardt and Handcock (2007), as well as the btergm package. We also discuss it and provide examples in the tergm tutorial.