# Pattern matching in differential equations

We have the following functional equation:
f(x*y)+f(x*(1-y))+f((1-x)*y)+f((1-x)*(1-y)) == f(x)+f(1-x)+f(y)+f(1-y)
Differentiating by x then y we get a second order differential equation which contains the pattern g(t)=f'(t)+tf''(t) three times with different expressions for t.

How can I change the occurences of the patterns to the appropriate g(.)?

@czsan: To display inline code, surround it within backticks `.

To display blocks of code, either indent them with 4 spaces, or select the corresponding lines and click the "code" button (the icon with '101 010'). Can you edit your question to do that?