Answer:
Follows are the solution to the given question:
Explanation:
Please find the correct question in the attached file.
[tex]\\ \text{ Premise 1:} \exists y Lby \\ \text{ Premise 2: }\exists x Lxb \\ \text{ Conclusion: } Lbb[/tex]
2.
Build a real tree with the premises and reject the end.
[tex](\exists y)Lby \ \ \ \ \ \ \ Premise 1 \\\\(\exists x)Lxb \ \ \ \ \ \ \ Premise 2 \\\\ \sim Lbb \ \ \ \ \ \ \ \ \ \ Conclusion \ \ rejection\\\\ Lba \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ 1 \exists D \\\\ Lcb \ \ \ \ \ \ \ \ \ \ \ \ \ \ 2 \exists D\\\[/tex]
The statement is INVALID because the tree is not shut down (because a branch is open)
3.
From the given model:
[tex]Domain={a,b,c}\\Ext(L)={ (b,a), (c,b)}[/tex]