# What's the meaning of the $\top$ symbol in a Hoare triple?

I'm studying program verification and came across the following triple:
$$\{\top\} \;P \; \{y=(x+1)\}$$ What's the meaning of the $\top$ symbol on the precondition? Does it mean $P$ can take any input?

The symbol $\top$, known as top, stands for "True". There is also a symbol $\bot$, known as bottom, which stands for "False". Top is always true, and bottom is always false. In your case, having a precondition that always holds is the same as having no precondition.