can+have+p.p vs. could+have+p.p

[btech86]

Hello there;

would anyone kindly explain the difference between can+have+pp and could+have+pp
"she can't have missed out on the program."
"she couldn't have missed out on the program."

 

[emsr2d2]

Depending on context (as always), both are possible.

 

[Raymott]

Note that we don't normally use 'can have + pp' in the positive. So you can use "could have + pp".
With the negative, "couldn't have" implies some sort of conditionality. In many cases, there's no real difference.