Can You Construct an Infinite Lattice with Each Integer Exactly Once?

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Discussion Overview

The discussion revolves around the construction of an infinite rectangular lattice that extends infinitely in both horizontal and vertical directions, with the goal of populating it with integers from 1 to infinity exactly once. Participants explore various methods for defining the lattice structure and the relationships between the numbers in different rows based on a sequence defined in the top row.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant proposes a method for defining a sequence across the top of the lattice and asks how many distinct lattices can be constructed under the condition that each integer appears exactly once.
  • Another participant challenges the clarity of the terms "top" and "upper left hand corner" in the context of an infinite lattice, suggesting that the assignment of integers is trivial if not properly defined.
  • A participant suggests a diagonal filling method for populating the lattice with integers, providing an example of how numbers can be arranged.
  • Another example is proposed based on prime decomposition, although one participant expresses dissatisfaction with this method, arguing it does not meet their criteria for a "basic operation" to define lower rows.
  • A participant describes their own construction of infinite lattices using a specific sequence from Sloane's Online Encyclopedia, detailing the operations used to define the integers in the lower rows based on the upper rows.
  • They provide a specific formula for the relationship between terms in the lattice and claim to have verified that all integers below a certain threshold appear exactly once in their construction.

Areas of Agreement / Disagreement

Participants express differing views on the clarity of the problem statement and the methods for constructing the lattice. There is no consensus on a single approach, and multiple competing methods and interpretations are presented.

Contextual Notes

Some participants note the ambiguity in defining the structure of the infinite lattice, particularly regarding the terms used to describe its orientation. Additionally, the validity of the proposed methods and their ability to populate the lattice with integers exactly once remains under discussion without a definitive resolution.

ramsey2879
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Suppose you have a rectangular lattice which extends infinitely both left to right and top to bottom and let the upper left hand corner be called the orgin. Problem for thought. Provide a first infinite sequence across the top of the lattice such that the nth lattice point to the right of the orgin contains the nth term of the sequence and define basic some operation that uniformly and completely defines the numbers assigned to the lower rows of the lattice based upon the terms above it so that the entire lattice points are predefined. How many of these lattices can you construct such that each of the integers from 1 to infinity will populate the lattice once and only once? There are in fact an infinite number such distinct lattices. Anyone care for an example or to give an example?
 
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ramsey2879 said:
Suppose you have a rectangular lattice which extends infinitely both left to right and top to bottom and let the upper left hand corner be called the orgin. Problem for thought. Provide a first infinite sequence across the top of the lattice such that the nth lattice point to the right of the orgin contains the nth term of the sequence and define basic some operation that uniformly and completely defines the numbers assigned to the lower rows of the lattice based upon the terms above it so that the entire lattice points are predefined. How many of these lattices can you construct such that each of the integers from 1 to infinity will populate the lattice once and only once? There are in fact an infinite number such distinct lattices. Anyone care for an example or to give an example?

With a lattice that is infinite in both directions, 'top' and 'upper left hand corner' don't make sense.

Assigning the integers to the half-plane is a pretty trivial exercise otherwise.
 
NateTG said:
With a lattice that is infinite in both directions, 'top' and 'upper left hand corner' don't make sense.

Assigning the integers to the half-plane is a pretty trivial exercise otherwise.

I think he means that it extends infinitely to the right and infinitely downward, but has an edge on the top and on the left - basically like N^2.

An example of such a lattice is the following, where we just fill diagonals with successive numbers:

1 2 4 7 .
3 5 8 .
6 9 .
10 .
.

Another might be based on prime decomposition (1 is placed arbitrarily):

1 2 4 6 8 . . .
3 9 15 21 . . .
5 25 35 55 . . .
7 49 77 91 . . .
11 121 143 . . .
. . .
 
Moo Of Doom said:
I think he means that it extends infinitely to the right and infinitely downward, but has an edge on the top and on the left - basically like N^2.

An example of such a lattice is the following, where we just fill diagonals with successive numbers:

1 2 4 7 .
3 5 8 .
6 9 .
10 .
.

Another might be based on prime decomposition (1 is placed arbitrarily):

1 2 4 6 8 . . .
3 9 15 21 . . .
5 25 35 55 . . .
7 49 77 91 . . .
11 121 143 . . .
. . .
Yes something like that is what I had in mind. I don't like the second since I don't think the numbers below are defined by what I consider to be "a basic operation" on the upper numbers. For the first example we have [tex]a_{i,j} = a_{i-1,j+1} + 1 = a_{i-1,j}*2 - a_{i-2,j} + 1.[/tex]

I have formed an infinite number of lattices by taking as the first row sequence A000201 from Sloane's Online Encyclopedia of sequences starting with tne nth term but subtracting
[tex]a_n -1[/tex] from each term. Then each underlying term is uniquely defined be the term immediately above by the operations of addition, multiplication and subtraction where the amounts of subtraction and addition are based upon the values of [tex]n[/tex] and [tex]a_n[/tex].
To wit sequence A000201 is 1,3,4,6,8,9,11,12,14,16,... and starting at term [tex]a_4[/tex] 5 is subtracted from each term to give 1,3,4,6,7,9,11,...

Regardless of the starting term the terms on the rows below are all below are then defined based upon n as follows:
[tex]A_{i,j} = \lfloor (A_{i-1,j}+a_{n} -n -1)*(phi + 1) - a_{n} +1 \rfloor[/tex] phi = sqrt(5) + 1)/2
I checked for n = 1 to 107 that all integers less than 54002 appear in each such lattice once and only once. And also that each term in the lower rows equals 3 times the next upper term minus the 2nd next upper term. I believe that the method works for all n such that each integer from 1 to infinity populates the lattice once and only once, but am still working on the proof.

My lattice based upon the 4th term as the starting term is
1,03,04,06,07,09,11...
2,08,10,15,18,23,29...
5,21,26,39,49,60,76...
...
 
Last edited:

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