@Dave 1. In the end only 1 will survive (after max of 2 rounds). i.e. P(A survives in end) + P(B survives in end) + P(C survives in end) = 1
2. Now, by shooting in air C increases his probability by your argument, which is not good for A. Thus, P(A shooting at C) should NOT be 0 if A is intelligent. 3. If it is not 0, P(C's survival) decreases (doesn't remain 0.49624). Please let me know if this is clear enough. On Sun, Jan 2, 2011 at 11:15 PM, Dave <dave_and_da...@juno.com> wrote: > @Salil: Just to make sure we are on the same page, A hits with 100% > probability, B hits with 50% probability, and C hits with 33% > probability. C shoots first, then B, then A. Then the shooting > continues among the survivors in that order until only one is > standing. > > If all three are alive and it is A's turn to shoot, he logically will > choose to shoot at B rather than C since B has a greater probability > of hitting him. Thus, your P(A shooting at C) = 0 if B is unhit when > it is A's turn. > > Similarly, if it is B's turn to choose between shooting at A or C, he > rationally will choose A since A will shoot at and hit B if A gets a > turn. So your P(B shooting at C) = 0 if A is unhit when it is B's > turn. > > If you dispute either of the above two paragraphs, please clealy state > your objection. > > Dave > > On Jan 1, 11:19 pm, Salil Joshi <joshi.sali...@gmail.com> wrote: > > @Dave, > > Yeah, I had read those numbers on internet as this puzzle is well known. > > However I am not convinced with the calculations because of following 2 > > points: > > > > 1) If C shoots in air, the probability of survival is more for the > > probabilities considered in the calculations with which A & B will shoot > at > > him. > > Now, if A & B are intelligent, they will know that increasing survival > > probability for C is bad for them (you can calculate survival probability > > for A & B in each case), and therefore they will shoot at C with higher > > probability than what they were planning earlier. > > > > 2) C's survival probability depends on P(A shooting at C) * 1 and P(B > > shooting at C) * 1/2. > > If C shoots at A, P(A shooting at C) is less by 33% and P(B shooting at > C) > > is more by 33%. So, if P(A shooting at C) dominates by logic in 1st > point, > > C's survival probability will be now more. > > > > > > > > > > > > On Sun, Jan 2, 2011 at 7:59 AM, Dave <dave_and_da...@juno.com> wrote: > > > @Salil: Working out the probabilities, we find that: > > > > > 1. If C initially shoots at A, C's probability of survival is ~ > > > 0.35867. > > > 2. If C initially shoots at B, C's probability of survival is ~ > > > 0.27679. > > > 3. If C initially shoots in the air, C's probability of survival is ~ > > > 0.49624. > > > > > Dave > > > > > On Jan 1, 11:30 am, Salil Joshi <joshi.sali...@gmail.com> wrote: > > > > @Rahul, > > > > As per my understanding, > > > > In any round P(C is dead) = P(A is alive * A shoots C * A's shot is > > > > accurate) + P(B is alive * B shoots C * B's shot is accurate) > > > > this is to be minimized. > > > > by not shooting at either A or B in 1st chance, how is this > probability > > > less > > > > for C? > > > > > > On Sat, Jan 1, 2011 at 10:43 PM, Salil Joshi < > joshi.sali...@gmail.com > > > >wrote: > > > > > > > @Rahul, > > > > > What purpose is served by wasting the shot? If C shoots at A or B, > at > > > least > > > > > some probability that C is dead in future will be reduced. > > > > > > > On Sat, Jan 1, 2011 at 10:14 PM, RAHUL KUJUR < > > > kujurismonu2...@gmail.com>wrote: > > > > > > >> @snehal: > > > > >> will the shooting take place in increasing order of accuracy of > > > hitting > > > > >> the target and is that at a time only one person can take a > shot??? > > > > >> if yes then > > > > >> @Salil: > > > > >> my answer would be the same as above. what C will do is that it > will > > > first > > > > >> let A and B kill each other first. > > > > >> After C wastes his shot it will be B's turn. B can kill C, but in > that > > > > >> case the turn would go to A and he would surely kill B. If B goes > > > after A, > > > > >> then B may hit it or miss it(as its probability of hitting is 50%) > > > > >> If B misses it > > > > >> then > > > > >> it depends on A whom to kill. A may kill B or C. A will try to > kill > > > one > > > > >> who is better shooter i.e. B as C is less likely to hit A. > > > > >> If B hits A then we are done. Round 1 is complete(as required in > the > > > > >> question) and C survives the first round. > > > > >> Look the problem is not that who gets killed at last but rather > what C > > > > >> should fire in the first round obviously to survive(as I > understood > > > the > > > > >> problem). It may happen that eventually C gets killed. But what > should > > > C > > > > >> shoot in first round to survive. > > > > > > >> -- > > > > >> You received this message because you are subscribed to the Google > > > Groups > > > > >> "Algorithm Geeks" group. > > > > >> To post to this group, send email to algoge...@googlegroups.com. > > > > >> To unsubscribe from this group, send email to > > > > >> algogeeks+unsubscr...@googlegroups.com<algogeeks%2bunsubscr...@googlegroups.com> > <algogeeks%2bunsubscr...@googlegroups.com> > > > <algogeeks%2bunsubscr...@googlegroups.com> > > > > >> . > > > > >> For more options, visit this group at > > > > >>http://groups.google.com/group/algogeeks?hl=en. > > > > > > > -- > > > > > > > -------- > > > > > Thanks & Regards > > > > > Salil Joshi. > > > > > CSE MTech II, IITB > > > > > A-414, Hostel 12 > > > > > +91.9819.442.865 > > > > > > > This is a confidential E-Mail. If it has reached you by mistake or > if > > > you > > > > > are not the intended receiver, please send it back to me. > > > > > > -- > > > > > > -------- > > > > Thanks & Regards > > > > Salil Joshi. > > > > CSE MTech II, IITB > > > > A-414, Hostel 12 > > > > +91.9819.442.865 > > > > > > This is a confidential E-Mail. If it has reached you by mistake or if > you > > > > are not the intended receiver, please send it back to me.- Hide > quoted > > > text - > > > > > > - Show quoted text - > > > > > -- > > > You received this message because you are subscribed to the Google > Groups > > > "Algorithm Geeks" group. > > > To post to this group, send email to algoge...@googlegroups.com. > > > To unsubscribe from this group, send email to > > > algogeeks+unsubscr...@googlegroups.com<algogeeks%2bunsubscr...@googlegroups.com> > <algogeeks%2bunsubscr...@googlegroups.com> > > > . > > > For more options, visit this group at > > >http://groups.google.com/group/algogeeks?hl=en. > > > > -- > > > > -------- > > Thanks & Regards > > Salil Joshi. > > CSE MTech II, IITB > > A-414, Hostel 12 > > +91.9819.442.865 > > > > This is a confidential E-Mail. If it has reached you by mistake or if you > > are not the intended receiver, please send it back to me.- Hide quoted > text - > > > > - Show quoted text - > > -- > You received this message because you are subscribed to the Google Groups > "Algorithm Geeks" group. > To post to this group, send email to algoge...@googlegroups.com. > To unsubscribe from this group, send email to > algogeeks+unsubscr...@googlegroups.com<algogeeks%2bunsubscr...@googlegroups.com> > . > For more options, visit this group at > http://groups.google.com/group/algogeeks?hl=en. > > -- -------- Thanks & Regards Salil Joshi. CSE MTech II, IITB A-414, Hostel 12 +91.9819.442.865 This is a confidential E-Mail. If it has reached you by mistake or if you are not the intended receiver, please send it back to me. -- You received this message because you are subscribed to the Google Groups "Algorithm Geeks" group. To post to this group, send email to algoge...@googlegroups.com. To unsubscribe from this group, send email to algogeeks+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/algogeeks?hl=en.
