Boolean statements

Given variables a, b, c, d, e, f and g of type integer.

Which of the following  expressions are equal to:

if (a < b) and (c < d) then

    e := f

else

    e := g;

Only in case a is less than b AND c is less than d, and only then, e takes the value of f. Otherwise e takes the value of g.

[A]

e := f;

if not (a < b) then

    e := g;

if not (c < d) then

    e := g;

This can be changed to...

if not (a < b) or not (c < d) then

    e := g

else

    e := f;

...or...

if (a >= b) or (c >= d) then

    e := g

else

    e := f;

...which is option [B].

f is assigned to e only in case a < b and c < d. Otherwise e gets the value of g.

Therefore equal to the given term.  

[B]

if (a >= b) or (c >= d) then

    e := g

else

    e := f;

See option [A].

[C]

e := g;

if a < b then

    e := f;

if c < d then

    e := f;

Not equal. f is assigned to e in case a is less than b OR c is less than d.

if (a < b) or (c < d) then

    e := f

else

    e := g;

[D]

if a < b then

    if c < d then

        e := f

    else

        e := g;

Not equal. What value is assigned to e in case a >= b?

[E]

e := g;

if not (a >= b) then

    e := f;

if c < d then

    e := f;

Not equal.

if not (a >= b) can be changed to if a < b.

e := g;

if a < b then

    e := f;

if c < d then

    e := f;

Same as option [C].