One can also consider what happens if one holds ''b'' constant and varies ''a''. In the symmetrical case {{nowrap|''b'' {{=}} 0}}, one observes a [[pitchfork bifurcation]] as ''a'' is reduced, with one stable solution suddenly splitting into two stable solutions and one unstable solution as the physical system passes to {{nowrap|''a'' < 0}} through the cusp point (0,0) (an example of [[spontaneous symmetry breaking]]). Away from the cusp point, there is no sudden change in a physical solution being followed: when passing through the curve of fold bifurcations, all that happens is an alternate second solution becomes available. | One can also consider what happens if one holds ''b'' constant and varies ''a''. In the symmetrical case {{nowrap|''b'' {{=}} 0}}, one observes a [[pitchfork bifurcation]] as ''a'' is reduced, with one stable solution suddenly splitting into two stable solutions and one unstable solution as the physical system passes to {{nowrap|''a'' < 0}} through the cusp point (0,0) (an example of [[spontaneous symmetry breaking]]). Away from the cusp point, there is no sudden change in a physical solution being followed: when passing through the curve of fold bifurcations, all that happens is an alternate second solution becomes available. |