John Baez wrote :

> In resource theories \$$x \le y\$$ often means "if you have \$$y\$$ you can use it to make \$$x\$$".

The aha moment LOL. So we are only looking at the possibility of production and not the actual process. I usually deal with actual processes so when I see flow diagrams I automatically start calculating yields which caused the confusion.

> I have a feeling that when you are writing \$$x \le y\$$ you are thinking \$$x \lt y\$$.

I am not sure what exactly your interpretation of \$$x \lt y\$$ is but you are probably right? LOL Following the flow, I would guess this would be the conversion of the actual process? The "or" in "less than or equal to" makes it into a possibility of production. But with just "less than" the conversion has made a choice of outcome?

So if \$$a+b \leq c \$$ where a,b,c are resources is a process that is possible, then the actual reaction would be \$$a+b \lt a+b+c\$$?