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The New Coffee Room

  1. TNCR
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  3. Puzzle time - don't waste braindead liberals

Puzzle time - don't waste braindead liberals

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  • jon-nycJ Offline
    jon-nycJ Offline
    jon-nyc
    wrote on last edited by
    #19

    Don’t add any hints

    Only non-witches get due process.

    • Cotton Mather, Salem Massachusetts, 1692
    1 Reply Last reply
    • bachophileB Offline
      bachophileB Offline
      bachophile
      wrote on last edited by
      #20

      Link to video

      1 Reply Last reply
      • jon-nycJ Offline
        jon-nycJ Offline
        jon-nyc
        wrote on last edited by
        #21

        I’ve almost got this just need to figure out one last piece when I can get to a desk

        Only non-witches get due process.

        • Cotton Mather, Salem Massachusetts, 1692
        KlausK 1 Reply Last reply
        • jon-nycJ jon-nyc

          I’ve almost got this just need to figure out one last piece when I can get to a desk

          KlausK Offline
          KlausK Offline
          Klaus
          wrote on last edited by Klaus
          #22

          @jon-nyc said in Puzzle time - don't waste braindead liberals:

          I’ve almost got this just need to figure out one last piece when I can get to a desk

          Reminds me of a famous quote from Fermat from 1637.

          I have discovered a truly marvelous proof of this, which this margin is too narrow to contain

          The proof of his famous conjecture was written down in 1995 after thousands of mathematicians spend their whole life working on the maths necessary to make that proof.

          1 Reply Last reply
          • jon-nycJ Offline
            jon-nycJ Offline
            jon-nyc
            wrote on last edited by jon-nyc
            #23

            Finally I think I have it.

            Lets call A0 Ax's actual position and A1 through A4 his reflected position off of each of the four mirrors. Same idea with L0-4.

            Draw out those 10 points, and draw the 25 line segments that start from Ax and all 4 of his reflections and go to Larry and all four of his reflections. Now, all but one of these segments will extend outside the arena, but the ones that do are the equivalent of a 'bank shot' encompassing one or more reflections in the mirrored surface.

            You can translate the midpoint of each of these segments to it's equivalent point within the arena, bu recognizing that it is the mirror image of the point across the nearest wall of the arena.

            This will get you 25 points within the arena. You soon notice that 9 of these fall out of duplicates. So you are left with 16. They seem to form a neat grid.

            I've not yet shown here that those 16 points are sufficient, though I convinced myself that as long as you choose the midpoints, you will also block equivalent shots between more distant reflections, which correspond to more zig-zaggy bank shots between Larry and Ax.

            For example, here I have shown visually how Ax shooting Larry's reflection in the bottom mirror is equivalent to him shooting actual Larry with the bank shot:

            Screen Shot 2020-10-17 at 9.15.08 AM.png

            But more than that, you see that the midpoint will also block the case where Ax shoots Larry using the same two walls, but does three banks instead of 1. Note this corresponds to Ax's reflection A1 shooting Larry's reflection L2:

            Screen Shot 2020-10-17 at 9.15.19 AM.png

            That point will stop all of the shots using just those two walls using an odd number of reflections. A distinct point will stop all that use an even number of reflections.

            Only non-witches get due process.

            • Cotton Mather, Salem Massachusetts, 1692
            1 Reply Last reply
            • jon-nycJ Offline
              jon-nycJ Offline
              jon-nyc
              wrote on last edited by
              #24

              That wasn’t correct. I need to fix it and repost.

              Only non-witches get due process.

              • Cotton Mather, Salem Massachusetts, 1692
              1 Reply Last reply
              • KlausK Offline
                KlausK Offline
                Klaus
                wrote on last edited by Klaus
                #25

                You are close. Many right ideas in your draft.

                1 Reply Last reply
                • jon-nycJ Offline
                  jon-nycJ Offline
                  jon-nyc
                  wrote on last edited by
                  #26

                  I know it’s the second example I drew out which I didn’t like.

                  Only non-witches get due process.

                  • Cotton Mather, Salem Massachusetts, 1692
                  1 Reply Last reply
                  • jon-nycJ Offline
                    jon-nycJ Offline
                    jon-nyc
                    wrote on last edited by
                    #27

                    I am confident my answer is right, just trying to show it’s exhaustive

                    Only non-witches get due process.

                    • Cotton Mather, Salem Massachusetts, 1692
                    1 Reply Last reply
                    • KlausK Offline
                      KlausK Offline
                      Klaus
                      wrote on last edited by Klaus
                      #28

                      I think it's not exhaustive. You get only 11 distinct BDLs that way, not 16.

                      1 Reply Last reply
                      • jon-nycJ Offline
                        jon-nycJ Offline
                        jon-nyc
                        wrote on last edited by
                        #29

                        I got 16. 25 possible segments, 9 fell out as redundant.

                        Only non-witches get due process.

                        • Cotton Mather, Salem Massachusetts, 1692
                        1 Reply Last reply
                        • KlausK Offline
                          KlausK Offline
                          Klaus
                          wrote on last edited by
                          #30

                          9 are obviously redundant. But there are 4 more that are redundant. Do you want me to illustrate that?

                          1 Reply Last reply
                          • jon-nycJ Offline
                            jon-nycJ Offline
                            jon-nyc
                            wrote on last edited by
                            #31

                            Not yet

                            Only non-witches get due process.

                            • Cotton Mather, Salem Massachusetts, 1692
                            1 Reply Last reply
                            • jon-nycJ Offline
                              jon-nycJ Offline
                              jon-nyc
                              wrote on last edited by
                              #32

                              Yes so the midpoints, shifted if necessary, of the following segments:

                              A0-L0
                              A0-L1
                              A0-L2
                              A0-L3
                              A0-L4
                              A1-L2
                              A1-L3
                              A1-L4
                              A2-L3
                              A2-L4
                              A3-L4

                              Where A0 and L0 are the positions of Ax and Larry respectively. and A1-4 and L1-4 are their apparent positions in the 4 mirrors that surround them.

                              Only non-witches get due process.

                              • Cotton Mather, Salem Massachusetts, 1692
                              1 Reply Last reply
                              • KlausK Offline
                                KlausK Offline
                                Klaus
                                wrote on last edited by
                                #33

                                Exactly. The detail that you presumably missed previously was that the situation is symmetric: The midpoint of A1-L2 is the same as A2-L1. That's why only 11 remain.

                                But those 11 aren't enough.

                                1 Reply Last reply
                                • jon-nycJ Offline
                                  jon-nycJ Offline
                                  jon-nyc
                                  wrote on last edited by
                                  #34

                                  I could put the arena on a coordinate system and define all the points of the 11 barriers in terms of Ax's coordinates x1,y1; Larry's coordinates x2,y2; and the width W and height(depth) H of the arena.

                                  Only non-witches get due process.

                                  • Cotton Mather, Salem Massachusetts, 1692
                                  1 Reply Last reply
                                  • jon-nycJ Offline
                                    jon-nycJ Offline
                                    jon-nyc
                                    wrote on last edited by jon-nyc
                                    #35

                                    That's what I was getting at earlier, wondering if they were exhaustive. I didn't look for higher-order reflections, assuming or hoping they'd collapse to the ones I'd defined. Give me some more time.

                                    Only non-witches get due process.

                                    • Cotton Mather, Salem Massachusetts, 1692
                                    1 Reply Last reply
                                    • KlausK Offline
                                      KlausK Offline
                                      Klaus
                                      wrote on last edited by Klaus
                                      #36

                                      If you want some data to play around with: I wrote down 10 lines of code to help me verify my method, which also supports your approach without many modifications (which shows that you are not far off from mine).

                                      For instance, for this setup:

                                      larry = (1.0,2.0)
                                      ax = (8.0,5.0)
                                      width = 10.0
                                      height = 6.0
                                      

                                      your approach yields the following 25 midpoints:

                                      [(4.5,3.5),(4.5,7.5),(4.5,1.5),(13.5,3.5),(3.5,3.5),(4.5,4.5),(4.5,8.5),(4.5,2.5),(13.5,4.5),(3.5,4.5),(4.5,-1.5),(4.5,2.5),(4.5,-3.5),(13.5,-1.5),(3.5,-1.5),(6.5,3.5),(6.5,7.5),(6.5,1.5),(15.5,3.5),(5.5,3.5),(-3.5,3.5),(-3.5,7.5),(-3.5,1.5),(5.5,3.5),(-4.5,3.5)]
                                      

                                      which, when shifted back, yield these 11 coordinates for BDLs:

                                      [(3.5,1.5),(3.5,3.5),(3.5,4.5),(4.5,1.5),(4.5,2.5),(4.5,3.5),(4.5,4.5),(5.5,3.5),(6.5,1.5),(6.5,3.5),(6.5,4.5)]
                                      
                                      1 Reply Last reply
                                      • jon-nycJ Offline
                                        jon-nycJ Offline
                                        jon-nyc
                                        wrote on last edited by jon-nyc
                                        #37

                                        I think I got it. I need to add two additional reflections for each of Ax and Larry which amount to the double reflections off the pair of mirrors at each corner.

                                        That gives me 36 segments, of which 20 drop out as redundant.

                                        Only non-witches get due process.

                                        • Cotton Mather, Salem Massachusetts, 1692
                                        1 Reply Last reply
                                        • jon-nycJ Offline
                                          jon-nycJ Offline
                                          jon-nyc
                                          wrote on last edited by jon-nyc
                                          #38

                                          This sketch shows the reflections for two arbitrary points.

                                          Screen Shot 2020-10-17 at 5.57.37 PM.png

                                          Only non-witches get due process.

                                          • Cotton Mather, Salem Massachusetts, 1692
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