hp 50 g simplify solutions

[Tugdual]

When I come across simplification questions, my first reaction is: How do you define "simple". Looks like there is not even consensus about that. May be a way to approach that would be to define the "energy" of an expression and seek for minimum but you're not certain the minimum would be "pleasant to read". The 50g actually defines a number of transformations instead of just a simplification.