So I'm reading Python Machine Learning by Sebastian Raschka, but I'm getting a little lost on an equation that appears multiple times in the book in two different forms. Here it is with (y) and (1-y) as indicator functions: [![enter image description here][1]][1] It then appears in this form with the initial (y) indicator missing. Where did it go?? Is it not important? My intuition tells me it needs to stay in the equation. [![enter image description here][2]][2] Lastly, here it is with an l2 penalty: << cannot post more than 2 links. sorry >> Can anyone help explain this discrepancy? What am I not understanding? [1]: https://i.sstatic.net/RS4PC.png [2]: https://i.sstatic.net/mYXo3.png