Candidate Elimination Question---Please help!

Question

Hi , I am doing a question on Candidate Elimination Algorithm. I am a little confused with the general boundary G.

Here is an example, I got G and S to the fourth case, but I am not sure with the last case.

1. Sunny,Warm,Normal,Strong,Warm,Same,EnjoySport=yes
2. Sunny,Warm,High,Strong,Warm,Same,EnjoySport=yes
3. Rainy,Cold,High,Strong,Warm,Change,EnjoySport=no
4. Sunny,Warm,High,Strong,Cool,Change,EnjoySport=yes
5. Sunny,Warm,Normal,Weak,Warm,Same,EnjoySport=no

What I have here is : S 0 :{0,0,0,0,0,0}

S 1 :{Sunny,Warm,Normal,Strong,Warm,Same}

S 2 , S 3 : {Sunny,Warm,?,Strong,Warm,Same}

S 4 :{Sunny,Warm,?,Strong,?,?}

G 4 :{Sunny,?,?,?,?,?,?,Warm,?,?,?,?}

G 3 :{Sunny,?,?,?,?,?,?,Warm,?,?,?,?,?,?,?,?,?,Same}

G 0 , G 1 , G 2 : {?,?,?,?,?,?}

What would be the result of G5? Is it G5 empty? {}? or {???Strong??) ?

Thanks

Answer 1

G5 is neither of those.

Note that {???Strong??} is not a specialisation of G4, so that's not a valid addition to the general boundary.

Rather, you would remove {Sunny,?,?,?,?,?} and {?,Warm,?,?,?,?} and replace them with minimal specialisations of each. So in this case, you would end up with:

G5 = {Sunny,?,High,?,?,?}, {Sunny,?,?,Strong,?,?}, {?,Warm,High,?,?,?}, {?,Warm,?,Strong,?,?}.