Kindly look at the questions again: Exercise $6\mathrm{.}4(1$ mark$)$

Answer the following multiple$-$choice question. Any number of answers $(0-4)$ can be correct.

Which of these statements about delete$-$relaxed planning are true?

We can efficiently compute the delete relaxation of a planning task.

We can efficiently determine if a delete$-$relaxed planning task has a solution.

In a delete$-$relaxed planning task, applying an operator twice has the same effect as applying it only once.

If $\backslash (\backslash$pi $\backslash )$ is a plan for a planning task and $\backslash (\backslash$pi$^\{+\}\backslash )$is the corresponding delete$-$relaxed plan, then $\backslash (\backslash$operatorname$\{$cost$\}(\backslash$pi$)=\backslash$operatorname$\{$cost$\}\backslash$left$(\backslash$pi$^\{+\}\backslash$right$)\backslash ).$

Note: This exercise is from the $2029$ Planning and Optimization exam.