Bistable point is defined as :
if(x1, y1) is a bistable point then :
f(x1,y) <= f(x,y) for all x,y and f(x,y1) <= f(x,y) for all x,y
While the global minima is defined as :
if (x1, y1) is a global minima then f(x1,y1) <= f(x,y) for all x,y
The book says every global minima is a bistable point, how can I prove it?