Ambiguity in Perceptron loss function (C. Bishop vs F. Rosenblatt)
I managed to find the  Bishop's version by unearthing! the Rosenblatt's 1962 Principles of neurodynamics, Page 110 book, so the Wikipedia's version must be the alternative one.





It is worth noting that the book also has a chapter on error back-propagation (page 292), which resembles the Wikipedia version, but I think it is not exactly the same.