## Sekiguchi's 17 Free Divisors

 F_a1 (aka Swallowtail) 16x4z-4x3y2-128x2z2+144xy2z-27y4+256z3
 F_b7 xy4-4x2y2z-2y3z+4x3z2+4xyz2+2z3
 F_h7 xy3z+y5+z3
 F_h3 8x3y4 +108y5 -36xy3z-x2yz2+4z3
 F_h5 x3y4 -y5+3xy3z+z3
 F_b5 xy4+y3z+z3
 F_h1 -100z3 +8x5z2-100x2yz2+8x7yz+120x4y2z+450xy3 z-135y5-230x3 y4-20x6y3-8x9y2
 F_b2 z(-2y3+4x3z+18xyz+27z2)
 F_b3 z(-2y3+9xyz+45z2)
 F_b4 z(9x2y2-4y3+18xyz+9z2)
 F_h6 x3y4+y5-2x4y2z-4xy3z+x5z2+3x2yz2+z3
 F_h2 100x3y4+y5+40x4y2z-10xy3z+ 4x5z2-15x2yz2+ z3
 F_b6 9xy4+6x2y2z -4 y3z+x3z2-12xyz2+4z3
 F_a2 2x6-3x4z+18x3y2-18xy2z+27y4+z3
 F_h4 y5-2xy3z +x2yz2+ z3
 F_b1 z(x2y2-4y3-4x3z+18xyz-27z2)
 F_h8 x3y4+y5-8x4y2z-7xy3z+16x5z2+12x2yz2+z3

## Various other free divisors

 Normal crossings xyz
 Whitney Umbrella + adjoint plane y(x2-y2z)
 The 4 lines xy(x+y)(x+yz)
 Cusp + plane x(y3-z2)
 Cone+plane (linear free) z(y2-xz)
 Non-Pham-Brieskorn free equisingular deformation x8+xy5+x6y2z
 Simis' quintic -x5 + 2x2y3 + xy4 + 3y5 + y4z
 Damon's Hessian Deformation of x4+y4 -x4 + y4- zx2y2
 Space curve disriminant 4z3+27(y2+x3+xz)2
 A3 Hyperplane arrangement (x2-y2)(x2-z2)(y2-z2)
 B3 Hyperplane arrangement xyz(x2-y2)(x2-z2)(y2-z2)
 H3 Hyperplane arrangement -xyz((b+1)x+by+z)(bx+y+(b+1)z)(x+(b+1)y+bz) ((b+1)x+by-z)(bx-y+(b+1)z)(-x+(b+1)y+bz) ((b+1)x-by+z)(-bx+y+(b+1)z)(x+(b+1)y-bz) ((b+1)x-by-z)(-bx-y+(b+1)z)(-x+(b+1)y-bz) with b=2cos(pi/5).
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