跳至內容

File:Tesseract2.svg

頁面內容不支援其他語言。
這個檔案來自維基共享資源
維基百科,自由的百科全書

原始檔案 (SVG 檔案,表面大小:188 × 239 像素,檔案大小:11 KB)


摘要

描述
English: Image of a three-dimensional net of a tesseract, created by Dmn with Paint Shop Pro.

The net of a tesseract is the unfolding of a tesseract into 3-D space. Let the dimension from left to right be labeled x, the dimension from bottom to top be labeled z, and the dimension from front to back be labeled y. Let coordinates by (x, y, z). Let the top cube have coordinates (0,0,1), the cube below it have coordinates (0,0,0), the cube in front of it have coordinates (0,−1,0), the cube behind it have coordinates (0,1,0), the cube to the left (−1,0,0), the one to the right (1,0,0). Let the cube below the central one have coordinates (0,0,−1) and the one at the bottom (0,0,−2).

The central cube (0,0,0) is seen to be connected to six other cubes, but when folded in 4-D every cube connects to six other cubes. The frontal cube (0,−1,0) connects in the −Y direction to (0,0,−2), in the +Y direction to (0,0,0), in the +X direction to (1,0,0), in the −X direction to (−1,0,0), in the +Z direction to (0,0,1), in the −Z direction to (0,0,−1).

There are twelve different ways in which the tesseract can be rotated (in 4-D) by 90 degrees in such a way that four of the cubes exchange positions cyclically while the remaining four cubes stay in place but rotate (in 3-D). For example, one 4-D rotation causes the following four-cube exchange: (0,0,1)→(0,0,0)→(0,0,−1)→(0,0,−2)→(0,0,1). Meanwhile, the same rotation causes cube (0,1,0) to rotate 90 degrees around the +X axis, the (0,−1,0) cube to rotate 90 degrees around the −X axis, the (1,0,0) cube to rotate 90 degrees in the −Y direction and the (−1,0,0) cube to rotate 90 degrees in the +Y direction.

The twelve 4-D rotations are:
1: (0,0,1)→(0,0,0)→(0,0,−1)→(0,0,−2)→(0,0,1),
9: (0,0,1)→(1,0,0)→(0,0,−1)→(−1,0,0)→(0,0,1),
10: (0,0,1)←(1,0,0)←(0,0,−1)←(−1,0,0)←(0,0,1),
11: (0,0,1)→(0,1,0)→(0,0,−1)→(0,−1,0)→(0,0,1),
12: (0,0,1)←(0,1,0)←(0,0,−1)←(0,−1,0)←(0,0,1).

Each 4-D rotation has a "dual" which is perpendicular to the 3-D rotation of the stationary cubes. There are six pairs of dual (4-D) rotations:

  • 1 ↔ 4,
  • 2 ↔ 3,
  • 5 ↔ 12,
  • 6 ↔ 11,
  • 7 ↔ 9,
  • 8 ↔ 10.

The dual of a 4-D rotation implies, by means of the right-hand rule, how the stationary cubes are supposed to rotate in 3-D.

Since there are eight cubes and each cube connects to six other cubes, then each cube has a pair of cubes to which it does not connect: (1) itself, and (2) its opposite. Thus there are four pairs of opposite cubes:
1: (0,0,1) ↔ (0,0,−1),
2: (0,0,0) ↔ (0,0,−2),
3: (−1,0,0) ↔ (1,0,0),
4: (0,−1,0) ↔ (0,1,0).

Each pair of opposite cubes aligns itself along opposite sides of one of four orthogonal axis of 4-D space. Therefore it is possible to establish a one-to-one onto mapping f between the unfolded positions of the cubes in 3-D and the canonical coordinates of their folded positions in 4-D, viz.

The canonical 4-D coordinates have been given labels corresponding to basis quaternions (and their negatives). Using these labels, the 4-D rotations can be expressed more simply as
1: K → 1 → −K → −1 → K,
2: K → −1 → −K → L → K,
3: I → J → −I → −J → I,
4: I → −J → −I → J → I,
5: −I → 1 → I → −1 → −I,
6: −I → −1 → I → 1 → −I,
7: −J → 1 → J → −1 → −J,
8: −J → −1 → J → 1 → −J,
9: K → I → −K → −I → K,
10: K → −I → −K → I → K,
11: K → J → −K → −J → K,
12: K → −J → −K → J → K.

All of these rotations follow a pattern AB→−A→−BA, so that each one can be abbreviated as an ordered pair (A,B). Then, each rotation can be abbreviated furthest as the product of the ordered pair of quaternions, which yields an imaginary quaternion:
1: (K,1) = K
2: (K,−1) = −K
3: (I,J) = K
4: (I,−J) = −K
5: (−I,1) = −I
6: (−I,−1) = I
7: (−J,1) = −J
8: (−J,−1) = J
9: (K,I) = J
10: (K,−I) = −J
11: (K,J) = −I
12: (K,−J) = I

The pairs of dual quaternions are then seen to have the following properties: the products of their single-quaternion abbreviations are always unity:

  • 1 ↔ 4 : K (− K) = 1,
  • 2 ↔ 3 : (−K) K = 1,
  • 5 ↔ 12 : (− I) I = 1,
  • 6 ↔ 11 : I (−I) = 1,
  • 7 ↔ 9 : (−J) J = 1,
  • 8 ↔ 10 : J (−J) = 1.
Each of the twelve rotations has a pair of candidate duals, but one of them is the reversal of the rotation, i.e. given rotation (A,B), its reverse is (A, −B), so it is disqualified as the dual of (A,B), leaving only one possible dual.
日期
來源 我個人以下列物件為基礎來創作: Tesseract2.png
作者 Traced by Stannered
其他版本 Tesseract2.png, Tesseract net Crooked House.svg
SVG開發
InfoField
 
SVG檔案的原始碼通過W3C驗證
 
vector image使用Inkscape創作。

授權條款

此作品已由其作者,中文維基百科專案的Dmn,釋出至公有領域。此授權條款在全世界均適用。

如果法律不適用時:
Dmn授予任何人有權利使用此作品於任何用途,除受法律約束外,不受任何限制。

說明

添加單行說明來描述出檔案所代表的內容

在此檔案描寫的項目

描繪內容

檔案歷史

點選日期/時間以檢視該時間的檔案版本。

日期/時間縮⁠圖尺寸使用者備⁠註
目前2007年4月1日 (日) 16:32於 2007年4月1日 (日) 16:32 版本的縮圖188 × 239(11 KB)Stanneredtweaking top cube
2007年4月1日 (日) 16:29於 2007年4月1日 (日) 16:29 版本的縮圖188 × 239(11 KB)Stannered'''Image of a three-dimensional net of a tesseract''', created by User:Dmn with Paint Shop Pro. The net of a tesseract is the unfolding of a tesseract into 3-D space. Let the dimension from left to right be labeled ''x'',

下列2個頁面有用到此檔案:

全域檔案使用狀況

以下其他 wiki 使用了這個檔案: