Hey i hope i am writing into right forum. I am banging my head against the wall almost for 2 hours and i can't figure out how the hack i can solve this.

i have this bayesian network:

Now i need to know how is this P( a | b ˄ ~d ˄ e) being "shortened" into this P( a | b ˄ ~d ) and this P( a | b ˄ ~c ˄ ~d ˄ e) into this P( a | b ˄ ~c).

Any help would be greatly apriciated.