Not sure about Canada, but German roads have been used for centuries, sometimes millennia and the ground is very packed and stable. Here in California, we blame earthquakes and El Nino.
I find their explanation wanting. Statements like "In the same way we can exclude ..." do not explain much of anything. Spoiler Alert: . . . . . . . . . . . . . .
Ivan's first two statements are either both true or both false. Given the rules, both must be true and the third statement is false. Dennis is not the thief.
Jumping to Ernie. His third statement is the same as Ivan's and must be false. Therefore his other two are true.
Look at Linda's third statement. It contradicts Ernie's second and must be false and the rest of her statements are true. Therefore Sylvia stole the candy.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
Ivan's first two statements are either both true or both false. Given the rules, both must be true and the third statement is false. Dennis is not the thief.
Jumping to Ernie. His third statement is the same as Ivan's and must be false. Therefore his other two are true.
Look at Linda's third statement. It contradicts Ernie's second and must be false and the rest of her statements are true. Therefore Sylvia stole the candy.
2) Not giving explicit instructions.
3) No intermediate quality inspections.
Can anyone else come up with any other mistakes?
A culturally appropriate dish I call Jewish Pizza.