CHAPTER 6 TWO-COLORED WALLPAPER PATTERNS 6.0 ...

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pg pg′ p b ′ 1g P P P P P R R R R R P R P R P Fig. 6.14 In these symmetry plans glide reflection vectors are not shown for the sake of simplicity, but you must indicate them in your work! 6.3 pm types (pm, pm′ , p b ′ 1m, p′ m, p b ′ g, c′ m) 6.3.1 Upgrading the glide reflection to reflection. Employing an old idea from 2.7.2 -- where we viewed a pma2 pattern as ‘half’ of a pmm2 pattern -- in the opposite direction, we are now ‘doubling’ the three pg-like patterns in figures 6.4, 6.9, and 6.11 into pm-like patterns by ‘fattening’ the glide reflections into reflections; that is, we reflect the pattern across every glide reflection axis without gliding the image. This process is bound to produce six two-colored pm-like patterns having reflection in one direction: indeed as we reflect across the glide reflection axes we have the option of a color effect either opposite to or same as that of the glide reflection (see also 6.3.2 and 6.3.5), so we end up with three × two = six pm types. We illustrate the process in the following six figures, indicating in each case the ‘original’ pg-like pattern and providing the name for the ‘new’ pm-like pattern. Make sure you can rediscover the old pg-like pattern inside the richer structure of the new pattern; there is more than mere nostalgia in our call: the old glide reflection is alive and well, ‘hidden’ under the new reflection and ready to play an important role in the classification process!
Fig. 6.15 pg → pm All reflections and hidden glide reflections preserve colors, so the new pattern is classified as a pm, despite being two-colored. Fig. 6.16 pg → p b ′ g
Page 1 and 2: © 2006 George Baloglou first draft
Page 3 and 4: Fig. 6.3 In the pattern of figure 6
Page 5 and 6: 6.0.4 Symmetry plans and types. Tri
Page 7 and 8: 6.1.2 Infinitely many color-reversi
Page 9 and 10: otations of both kinds, the corresp
Page 11 and 12: eversing 90 0 rotation -- not to me
Page 13: Fig. 6.13 In view of these facts, t
Page 17 and 18: Fig. 6.18 pg′ → pm′ All refle
Page 19 and 20: produced six pm-like two-colored wa
Page 21 and 22: 6.3.4 Translations and hidden glide
Page 23 and 24: 6.4 cm types (cm, cm′ , p c ′ g
Page 25 and 26: Fig. 6.28 pm′ → cm′ Fig. 6.29
Page 27 and 28: Fig. 6.31 p b ′ 1 Fig. 6.32 p b
Page 29 and 30: So, while our first two colorings i
Page 31 and 32: pattern ‘look the same’. It’s
Page 33 and 34: p c ′ g p c ′ m R P R P R P R P
Page 35 and 36: Fig. 6.42 pg′ → p2′ Fig. 6.43
Page 37 and 38: proof will be given in section 7.6.
Page 39 and 40: Fig. 6.48 pg → pgg Fig. 6.49 pg
Page 41 and 42: So far so good: we obtained four tw
Page 43 and 44: This is a demonstration of a signif
Page 45 and 46: pg′ g ′ pgg′ pgg′ Fig. 6.56
Page 47 and 48: You should compare these pgg symmet
Page 49 and 50: Fig. 6.61 pg → pmg Fig. 6.62 pg
Page 51 and 52: last two types, offspring of p b
Page 53 and 54: Fig. 6.68 p b ′ mg 6.7.4 Symmetry
Page 55 and 56: Fig. 6.70 pmg → pmm Somewhat conf
Page 57 and 58: The two patterns in figures 6.72 &
Page 59 and 60: Fig. 6.77 p b ′ mm → c′ mm Wh
Page 61 and 62: p b ′ gm p b ′ mm p b ′ gm Fi
Page 63 and 64: Fig. 6.80 pmg → pmm → cmm Fig.
Page 65 and 66:
Fig. 6.84 p b ′ gg → p b ′ gm
Page 67 and 68:
Due to not-that-obvious color incon
Page 69 and 70:
p c ′ mm p c ′ mg cm′ m ′ F
Page 71 and 72:
Fig. 6.93 pm′ Fig. 6.94 cmm′
Page 73 and 74:
Fig. 6.97 p b ′ gm You should be
Page 75 and 76:
6.10 p4 types (p4, p4′ , p c ′
Page 77 and 78:
Fig. 6.101 p4′ Fig. 6.102 p c ′
Page 79 and 80:
6.10.5 Symmetry plans. We use ‘st
Page 81 and 82:
twofold rotation at C, must both be
Page 83 and 84:
p4g p4′ g ′ m p4g′ m ′ p4
Page 85 and 86:
Fig. 6.111 We see that the p4m may
Page 87 and 88:
Fig. 6.113 pm′ m ′ 2 → p4m′
Page 89 and 90:
6.12.3 Further examples. Our ‘tri
Page 91 and 92:
consistent with color! As a consequ
Page 93 and 94:
Predictably, fourfold centers prese
Page 95 and 96:
must have the same effect on color
Page 97 and 98:
Fig. 6.124 p31m′ 6.15 p3m1 types
Page 99 and 100:
Fig. 6.126 p3m′
Page 101 and 102:
p3m1 types. They are not that cruci
Page 103 and 104:
and dots, respectively): Fig. 6.129
Page 105 and 106:
6.17 p6m types (p6m, p6′ mm′ ,
Page 107 and 108:
at the intersection of two reflecti
Page 109 and 110:
Fig. 6.136 p6m′ m ′ In this exa
Page 111 and 112:
Finally, some triangles inside the
Page 113 and 114:
6.18 All sixty three types together
Page 115 and 116:
cm cm′ p c ′ g p c ′ m (II) 1
Page 117 and 118:
cmm cm′ m ′ cmm′ p c ′ mm p
Page 119 and 120:
p4m p4′ mm′ p4′ m ′ m p4m
Page 121:
p6m p6′ m ′ m p6m′ m ′ p6
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CHAPTER 6 TWO-COLORED WALLPAPER PATTERNS 6.0 ...

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