Mathematical Conjectures

1.
A mathematician ,logician ,physicist and a engineer are traveling in a train, they see a some cows grazing

Physicist : look there so many black cows.
Mathematician :No, actually there is at least one black cow in that group.
Logician : No, No, don't get confused , there exist at least one cow whose one side is black.
Engineer : Look, there lots of sheep :P

2.
One Mathematician to another : Do you believe in one god ?
Answer : Yes , but up to isomorphism.

3.
How many engineers it takes to put a new bulb ?
Answer : One , himself

4.
Houseabzar's( A professor whose existence is proved) proof of Cayley's theorem : Every matrix satisfies its characteristic polynomial
Proof :
Kudh ka satisfy nahi karega to kiska karega ?

5.

When someone asks a mathematician, a physicist and a engineer to prove all natural numbers are prime, how do they go about it.

Mathematician : 2 is a prime, 3 is a prime so by induction all natural numbers are prime.
Physicist : 2 is prime , 3 is prime , 4 experimental error , 5 is a prime and we have proved that all natural numbers are prime with 25% error.
Engineer : 2 is prime, 3 is a prime , 4 is a pirme ,5 is a prime , 6 is a prime and so on