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superprismatic

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Posts posted by superprismatic

  1. A message is written in the cells of

    a rectangle having six rows and eight

    columns. A piece of cardboard with

    twelve holes cut out is placed over

    this and the twelve letters exposed

    read off. The cardboard is given a

    180 degree turn and the next twelve

    letters read off. At this point the

    cardboard is turned over around the

    vertical axis and twelve more letters

    are read off. A final turn of 180

    degrees allows the last 12 letters to

    be read off. The result is: UNOLU

    WUPNU ELGDH RDGHW EDEOL HTELH

    TYEYP NAAWA SIOAO WAE. Read the

    message.

    SUPERPRISMATIC CLARIFICATIONS:

    (1) The message is written in by rows,

    left-to-right and top row to bottom

    row.

    (2) The sets of twelve are read off

    left-to-right and top-to-bottom.

    (3) The cryptogram is written in

    groups of five for easy reading.

    The spaces are irrelevant.

    (4) Remember that the cutouts must

    be designed so that any letter is

    exposed in one, and only one, of the

    four orientations of the piece of

    cardboard

    (5) It might be instructive to

    design such a scheme yourself out of

    graph paper to see how to make good

    cutouts and to see how letters are

    scrambled by it.

  2. Circular hopscotch is played on six

    squares arranged in a circle. A coin

    is tossed and a player starting on

    square 1 jumps, advancing either 1 or

    2 squares according as the coin falls

    head or tail. When he lands on square

    6, he is 'out'. Each player gets a

    score equal to the number of squares

    stood on or passed over during his

    turn. (Thus the only possible scores

    are multiples of 6.) What is the

    average number of points a player may

    expect to score?

    SUPERPRISMATIC CLARIFICATION:

    Each advancement ( 1 or 2 squares)

    is preceded by a separate coin toss.

    That is to say, a single coin toss

    does not control all the jumps a

    player makes.

  3. [5, 12, 23, 10, 28, 4, 11, 11, 12, 4, 28, 19, 21, 12, 12, 27, 29, 11,

    11, 21, 12, 18, 29, 24, 23, 23, 12, 28, 10, 28, 29, 0, 2, 21, 2, 23,

    14, 28, 10, 18, 21, 4, 2, 28, 2, 4, 6, 23, 29, 27, 14, 29, 6, 19, 10, 28, 5, 28, 23, 29, 24]

    basically i wrote an algorithm that tries random positions until it finds one that works.

    (the 0 would be the king)

    I did a depth-first tree search. When I reorder the couples to place, I find that I can get very many solutions. I had hoped that someone would come up with a more enlightened approach than the ones you and I found.

  4. Check that real quick...the following:

    Should have read:

    We know that BOTH X AND Y are integral. So we know that x-y2 = y.

    Please explain further. If x and y are both integral, all I can see is that x-y2 is integral.

  5. If he is hosting several different parties do they need to be seated apart according to their anniversary at all parties or just at the party for their anniversary party?

    This is just for one of his many parties. All attendees are celebrating their anniversaries on the date of the dinner. The poor chief of protocol has to make the seating chart for all the other dinners as well! If you can find a good algorithm for him to use, you will simplify his life enormously!

  6. Clarify:

    .

    1. Since the table is round, between any two persons there are two sets of intervening people.
      Do we always take the smaller number?
      Doh! :duh: Forget that one ... but,
      .
    2. The King sits after all the spacings have been set.
      So the King does not apply to the separation count?

    To be specific, if a couple are on either side of the king, they are celebrating their 2nd anniversary.

    So, the king counts in the separation. I hope this clears it up.

  7. A benevolent king hosts wedding

    anniversary dinners for some of

    his subjects on several days

    each year. He has a 61-seat

    round table at which to seat

    30 couples who are celebrating

    their wedding anniversaries on

    the day of the dinner. He has

    decreed that each couple will

    be seated N-seats away from each

    other if they are celebrating

    their Nth anniversary.

    So, for example, if a couple

    has been married 1 year, they

    will be seated next to each

    other; married 2 years and they

    will have one person between them;

    etc. The king will sit at the

    one remaining seat. Imagine that

    you are the king's chief of

    protocol and you are given the

    task of arranging the seating

    for the 30 couples with the

    following anniversary distribution:


    # couples years married
    2 2
    2 4
    1 5
    1 6
    2 10
    2 11
    3 12
    1 14
    1 18
    1 19
    2 21
    3 23
    1 24
    1 27
    4 28
    3 29
    [/code]

    Being a Mathematics buff, you

    realize that this can be done

    because 61 is a prime. So, in what

    order do you seat the 60 guests?

  8. Oh that's true, I had forgotten about the quadratic formula, thx.

    But using the formula will create 2 different set of answers

    for:

    * f=(xy + sqrt(x2y2 + 4xy))/(2y)

    * f=(xy - sqrt(x2y2 + 4xy))/(2y)

    So it's starting to get more complex, but I'll give it a try

    You can forget the second one. After all, it is negative and it is clear that the solution must be positive.

  9. Members of a certain gang communicate

    with each other by means of the

    following system. The square root of

    an agreed-upon integer is extracted

    and carried out to a number of decimal

    places equal to the length of the

    message. Then each letter of the

    message is advanced (cyclically) in

    the normal alphabetic sequence a

    number of places given by the

    corresponding digit of the decimal

    part. For example, if the number

    agreed upon were 2, the word STOP

    would be enciphered as WUSR since

    Sqrt(2)=1.4142 to four decimal places.

    One day a detective found the

    following message on the body of a

    gangster slain by a member of a rival

    mob: TJYSZPVM OS FBIPI. He assumed

    (correctly) that this began PASSWORD

    IS. What is the password?

    SUPERPRISMATIC ANECDOTE ABOUT THIS:

    I know of two solutions to this --

    the one Penney intended as well as

    one that two smart co-workers of his

    found. They found a 31-digit integer

    which also gave a (different) common

    English word as the password. For

    this to happen, of course, the

    fractional part of its square root

    must begin with the same ten decimal

    digits that Penney's gave, then

    somehow differ in the next five.

    A super-hard secondary problem would

    be to find this 31-digit number. By

    the way, I don't know what that

    31-digit number is -- I only know

    what password it produces.

  10. By the way, I found my solution wrong... sorry 4 that

    I rechecked the algebra and I got stuck "somewhere"

    Having that

    f(x, y) = x + 1/(y + 1/f(x, y)) ......... 1

    I reduce as follows, .... I replaced f(x, y) with only f

    f = x + 1/(y + 1/f) .................. 1

    f = x + 1/((yf + 1)/f)

    f = ((xyf + x)/f + 1)/((yf + 1)/f)

    f = ((xyf + x + f)/f)/((yf + 1)/f)

    f = (xyf + x + f)/(yf + 1)

    yf2 + f = xyf + x + f

    yf2 = xyf + x

    yf2 - xyf - x = 0 .......... 2

    I believe equation 2 (the last reduction) can be factorized to have an expression f = g(x, y) where g(x, y) doesn't have f as part of it. Unfortunately, I haven't been able to factorize the expression, so I'm not even sure if that's possible.

    If possible, the f = g(x, y) could then be sustituted in the f(p, q) - 3f(r, s) = 1/2 expression, getting an equation involving the p, q, r, s parameters and then any combination of values for p, q, r, s that satisfies the equation is a solution.

    If anyone is able to factorize equation 2 please let me know.

    *Note: Is easier to follow the reductions I did if writing them into paper to see the algebraic form. All the parenthesis in here make it harder to follow.

    Use the quadratic formula to get f=(xy + sqrt(x2y2 + 4xy))/(2y).

  11. N = 521

    A full period of the Fibonacci sequence modulo 521 is:

    0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144, 233, 377, 89, 466, 34, 500, 13, 513, 5, 518, 2, 520, 1

    When placed in ascending order, you get

    0, 1, 1, 1, 2, 2, 3, 5, 5, 8, 13, 13, 21, 34, 34, 55, 89, 89, 144, 233, 377, 466, 500, 513, 518, 520

    Assigning to each letter,

    A 0

    B 1

    C 1

    D 1

    E 2

    F 2

    G 3

    H 5

    I 5

    J 8

    K 13

    L 13

    M 21

    N 34

    O 34

    P 55

    Q 89

    R 89

    S 144

    T 233

    U 377

    V 466

    W 500

    X 513

    Y 518

    Z 520

    This is the correct key for encoding and decoding the text presented in the question.

    mmiguel1's got it!

  12. I'm not sure that I understand the instruction in this puzzle. Is the following interpretation of the problem correct?

    1) A number N is chosen, where N is larger than the largest number in the cipher code.

    2) The fibonnaci series F(i) modulo N has a period of 26, meaning that for any index i, F(i) mod N == F(i + 26) mod N

    3) The list of 26 values from within 1 period is sorted in ascending order, and each number assigned a letter according to its ordinal index (smallest number is A, second smallest is B, and so on).

    4) This transformation is then applied to "Gardening is just a soil sport" to get ( 3 0 89 1 2 34 5 34 3/ 5 144 / 8 377 144 233 / 0 / 144 34 5 13 /144 55 34 89 233 )

    5) Find N

    PS. Also, does this sequence start at 1 or 0? Many references for the fibonnacci series start at 0.

    Your interpretation in 1 through 5 is correct. The sequence starts with 1, although that may not matter if 0, 1, 1 occurs in the 26-long cycle (because of your clarification #3). Also, if any number occurs more than once in the cycle, more than one letter is assigned to it.

  13. The value of the sequence 1, 2, 3, 5,

    8, ... , where each member is the sum

    of the two preceding, are reduced

    mod N; i.e., if any value is greater

    than N, N is subtracted. The

    resulting sequence has period 26, and

    the values, in numerical order, are

    assigned to the letters A to Z. Note

    that by this scheme the same number

    may represent more than one letter.

    The message, "Gardening is just a soil

    sport," converted into numbers by this

    process becomes: 3 0 89 1 2 34 5 34 3

    / 5 144 / 8 377 144 233 / 0 / 144 34

    5 13 / 144 55 34 89 233. Find N.

    SUPERPRISMATIC CORRECTION: "greater

    than" should be "greater than or equal

    to" in the explanation of "mod N" in

    the first sentence. Walter Penney

    was fallible.

  14. In the game of Subtract-a-Square two

    players take alternately from a pile

    of counters, the only restriction

    being that the number taken must be

    a perfect square. The player wins

    who succeeds in getting the last

    counter. How many should a player

    take if there are now 50 counters

    in the pile?

  15. I need my day's allowance of Walter Penney puzzle!

    Lemma: if the boy can reduce the groups on the daisy to an even number of 1's, an even number of 2's, an even number of 3's, or any combination of even groups of 1 to 3, he can win. Likewise, if the girl can reduce the groups to combination of even groups of 1 to 3, she can win.

    Start from the group of 8, let the boy pick the fourth petal, leaving the daisy with groups of 2, 3, and 4. You can easily see that doesn't matter what the girl pick next, the boy can reduce it to his winning combination within 1 move or 2 moves.

    You found a second solution. Penney gave another.

    Take 1 from the end of the 8, leaving 7 and 2. It works as well.

  16. Two lovers decide to test their love

    with a daisy. The particular daisy has

    13 petals, and they agree to pluck

    alternately, taking either one petal or

    two adjacent petals. The boy picks

    one, saying, "She loves me." The girl

    picks two adjacent petals, leaving

    groups of 8 and 2, saying, "He loves me

    not." How should the boy continue if

    he wants to end up in love in spite of

    any move his opponent (?) makes?

    SUPERPRISMATIC CLARIFICATION: The boy

    must pick the last of the petals to get

    what he wishes. Also, "adjacent petals"

    refers to adjacency on the original

    13-petal configuration in which each

    petal only has 2 adjacent petals -- one

    on either side.

  17. The numbers from 1 to 12 are written on

    the faces of a cube, two numbers to a

    face, in such a way that the sum of the

    numbers on any face is the same as the

    sum of the numbers on the opposite face.

    One of the numbers on the top face is

    selected, the cube rolled 90 degrees so

    that one of the adjacent faces comes on

    top, a number selected from this face,

    etc. The sequence 2, 1, 5, 3, 4, 7, 2,

    10, 6, 11, 8, 9, 12, 3, 11, 9, 10, 7,

    11, 12, 4, 1, 6, 5, 7 is generated in

    this manner. How are the numbers

    arranged on the face of the cube?

    The word "face" in the last sentence should be "faces"

  18. The numbers from 1 to 12 are written on

    the faces of a cube, two numbers to a

    face, in such a way that the sum of the

    numbers on any face is the same as the

    sum of the numbers on the opposite face.

    One of the numbers on the top face is

    selected, the cube rolled 90 degrees so

    that one of the adjacent faces comes on

    top, a number selected from this face,

    etc. The sequence 2, 1, 5, 3, 4, 7, 2,

    10, 6, 11, 8, 9, 12, 3, 11, 9, 10, 7,

    11, 12, 4, 1, 6, 5, 7 is generated in

    this manner. How are the numbers

    arranged on the face of the cube?

  19. The polynomial X23+X+1 can be

    expressed as the product of 2 factors.

    If the powers of X, excluding the

    constant term, in one of these factors

    is converted into letters (1=A, 2=B,

    etc.), it is observed that these letters

    can be anagrammed into a three-word

    phrase meaning, with a certain stretch

    of the imagination, "a peculiarity of a

    seat in a church gallery." What is the

    phrase?

    SUPERPRISMATIC CLARIFICATION: Perhaps

    the word "powers" should be replaced

    by "exponents" to better nail down the

    intent of the puzzle.

    SUPERPRISMATIC OBSERVATION: Walter

    Penney did not have access to computer

    algebra software!

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