The Mathematics of Ceramics A/P Helmer Aslaksen Dept. of Mathematics National Univ. of Singapore www.math.nus.edu.sg aslaksen@math.nus.edu.sg What does math have to do with ceramics? What is math? Math is the abstract study of patterns What is a pattern? Concrete geometrical patterns or abstract numerical or logical patterns What is abstract study? Generalize to get the underlying concept Where in Singapore is this? Why are these patterns nice? Symmetry What is symmetry? Most people think of vertical mirror symmetry (left/right) What is symmetry in general? A pattern is symmetric if it is built up from related parts A plane pattern has a symmetry if there is an isometry of the plane that preserves the pattern What is an isometry? An isometry of the plane is a mapping that preserves distance, and therefore shape Translation A translation moves a fixed distance in a fixed direction Reflection A reflection flips across an axis of reflection Rotation A rotation has a centre of rotation and an angle of rotation N-fold rotation If the angle is θ and n = 360o/θ is a whole number, then we call the rotation an n-fold rotation Rotational symmetry Order of Rotation Angle of Rotation 2 180° 3 120° 6 60° Figure Symmetry Regions Glide reflection A glide reflection is a combination of a reflection and a translation Four types of isometries Translation Reflections Rotations Glide reflections Symmetric patterns A plane pattern has a symmetry if there is an isometry of the plane that preserves it. There are three types of symmetric patterns. Rosette patterns (finite designs) Frieze patterns Wallpaper patterns Rosette patterns Leonardo’s Theorem: There are two types of rosette patterns. Cn, which has n-fold rotational symmetry and no reflectional symmetry Dn, which has n-fold rotational symmetry and reflectional symmetry Examples of rosette patterns Frieze patterns Frieze patterns are patterns that have translational symmetry in one direction We imagine that they go on to infinity in both directions or wrap around Frieze Patterns Examples of frieze patterns No sym Half turn Hor ref Ver ref Glide ref Hor and ver ref Glide ref and ver ref LLLL NNN DDD VVV HHH Wallpaper There are 17 types of wall paper patterns What does this have to do with arts? Every culture has a preference for certain symmetry type of patterns. The important thing is not the motif in the patterns, but the symmetry types. This can be used to date objects and detect connections between different cultures. Ming ceramics We will study Ming ceramics as an example No symmetry The p111 pattern (no symmetry) Horizontal reflection The p1m1 pattern (horizontal reflection) Vertical reflection The pm11 pattern (vertical reflection) Half turn The p112 pattern (half turn) Horizontal and vertical reflection The pmm2 pattern (horizontal and vertical reflections) Glide reflection and vertical reflection The pma2 pattern (glide reflection and vertical reflection) Glide reflection The p1a1 pattern (glide reflection) Analysis-Ming Porcelains 66 Seven Types of Frieze Pattern 60 40 29 21 20 20 0 pm11 p111 p1a1 p112 13 pma2 Frieze Patterns Types 9 pmm2 1 p1m1 Analysis-Ming Porcelains Distribution of Frieze patterns on Ming Porcelains Top 12% Body 24% Top Rim 33% Foot Ring 12% Base 19% Analysis-Ming Porcelains Distribution of Frieze Patterns on Ming Porcelains 25 20 15 10 5 0 Top Rim Top Body Base Foot Ring Area on Ming Porcelains p111 p112 p1a1 pm11 pmm2 pma2 p1m1 Analysis-Ming Porcelains Distribution of Frieze Patterns on Ming Porcelains in Different Periods 12 10 8 6 4 2 Period Top Rim Top Body Base Foot Ring C T& W an li Ji aj in g e en gd Zh hi H on gz a he ng hu C en gt on g e Zh Xu an d gl e Yo n u on gw H Yu an 0 Analysis-Ming Porcelains Distribution of Frieze Patterns on Ming Porcelains in Different Time Periods 12 10 8 6 4 2 0 Yuan Yongle Xuande Jiajing Wanli Tim e Pe riod Top Rim Top Body Base Foot Ring T&C Analysis-Ming Porcelains Distribution of Frieze Patterns Types in Different Time Periods 16 14 12 10 8 6 4 2 0 Yuan Yongle Xuande Jiajing Wanli Time Period p111 p112 p1a1 pm11 pmm2 pma2 p1m1 T&C Peranakan Ceramics We also looked at the Peranakan ceramics at the Asian Civilisations Museum in Singapore No symmetry The p111 pattern Vertical reflection The pm11 pattern Half turn The p112 pattern Horizontal and vertical reflection The pmm2 pattern Glide reflection and vertical reflection The pma2 pattern pma2 pm11 Glide reflection The p1a1 pattern Analysis-Peranakan Porcelains 50 Seven Types of Frieze Pattern 50 40 30 20 13 7 10 0 1 pm 11 p111 p112 p1a1 1 pm m 2 Frieze Patterns Types 1 pm a2 0 p1m 1 Analysis-Peranakan Porcelains Analysis- Peranakan Porcelains Distribution of Frieze Patterns on Peranakan Porcelains 35 30 25 20 15 10 5 0 Top Rim Top Body Base Foot Ring Area on Peranakan Porcelains p111 p112 p1a1 pm11 pmm2 pma2 p1m1