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When is the algorithm concept pertinent – and when not? Thoughts about algorithms and paradigmatic examples, and about algorithmic and non-algorithmic mathematical cultures1

  • 1 The following essay was originally presented as a contribution to the International Conference on History of Ancient Mathematics and Astronomy "Algorithms in the Mathematical Sciences in the Ancient World", held in Xi'an, 23–29 August 2015. Given its character as an invitation to reflection and discussion I have preferred to leave much of the style of an oral presentation
  • For Karine hard-working scholar who always finds time for friendship "Until some decades ago, it was customary to discuss much pre-Modern mathematics as "algebra", without agreement between workers about what was to be understood by that word. Then this view came under heavy fire, rarely with more precision. Now, instead, it has become customary to classify pre-Modern practical arithmetic as "algorithmic mathematics". In so far as any computation in several steps can be claimed to follow an underlying algorithm (just as it can be explained from an "underlying theorem", for instance from proportion theory, or from a supposedly underlying algebraic calculation), this can no doubt be justified. Traditionally, however, historians as well as the sources would speak of a rule. The paper first goes through some of the formative appeals to the algebraic interpretation – Eisenlohr, Zeuthen, Neugebauer – as well as some of the better argued attacks on it (Rodet, Mahoney). Next it asks for the reasons to introduce the algorithmic interpretation, and discusses the adequacy or inadequacy of some uses. Finally, it investigates in which sense various pre-modern mathematical cultures can be characterized globally as "algorithmic", concluding that this characterization fits ancient Chinese and Sanskrit mathematics but neither early second-millennium Mediterranean practical arithmetic (including Fibonacci and the Italian abbacus tradition), nor the Old Babylonian corpus."

    Citation: Jens Høyrup. When is the algorithm concept pertinent – and when not? Thoughts about algorithms and paradigmatic examples, and about algorithmic and non-algorithmic mathematical cultures1[J]. AIMS Mathematics, 2018, 3(1): 211-232. doi: 10.3934/Math.2018.1.211

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  • For Karine hard-working scholar who always finds time for friendship "Until some decades ago, it was customary to discuss much pre-Modern mathematics as "algebra", without agreement between workers about what was to be understood by that word. Then this view came under heavy fire, rarely with more precision. Now, instead, it has become customary to classify pre-Modern practical arithmetic as "algorithmic mathematics". In so far as any computation in several steps can be claimed to follow an underlying algorithm (just as it can be explained from an "underlying theorem", for instance from proportion theory, or from a supposedly underlying algebraic calculation), this can no doubt be justified. Traditionally, however, historians as well as the sources would speak of a rule. The paper first goes through some of the formative appeals to the algebraic interpretation – Eisenlohr, Zeuthen, Neugebauer – as well as some of the better argued attacks on it (Rodet, Mahoney). Next it asks for the reasons to introduce the algorithmic interpretation, and discusses the adequacy or inadequacy of some uses. Finally, it investigates in which sense various pre-modern mathematical cultures can be characterized globally as "algorithmic", concluding that this characterization fits ancient Chinese and Sanskrit mathematics but neither early second-millennium Mediterranean practical arithmetic (including Fibonacci and the Italian abbacus tradition), nor the Old Babylonian corpus."


    One of the main research areas of differential geometry is the characterization of curves in Euclidean, Minkowski, or other special spaces by analyzing them according to different frame such as Frenet, Bishop, etc.

    Although the Serret-Frenet frame is useful for the analysis of curves, this frame cannot be defined at points where the second derivative of the curve is equal to zero. This has led to the popularization of orthonormal frame systems defined along a curve, which have been proposed as an alternative to the Frenet frame. In this way, the frame can be defined at points with this property and enables any space curve to be analyzed. One of these alternative frames, the Bishop frame, offers a more suitable option, especially when the torsion is zero or when the effect of torsion needs to be minimized. The advantages of the parallel frame and its comparison with the Frenet frame in 3-dimensional (3D) Euclidean space were given and studied by Bishop [1]. The Bishop frame has many applications in computer graphics and biology. For example, the Bishop frame can be used to predict the shape of DNA sequences or to control virtual cameras in computer graphics. It provides clearer geometric modeling by avoiding the analysis of torsional effects in the double-helical structure of DNA [2]. It is, therefore, of great importance to identify new types of curves and characterize them in different frames.

    Helices appear in many applications, so the most common way to characterize curves is to determine whether they are general helices, cylindrical helices, or slant helices. A curve with a helix in E3E31 is characterized by the property that the tangent vector field forms a constant angle with a constant direction. Lancret's theorem proves that the ratio of torsion and curvature of a helix is constant [3]. The helix was generalized by Hayden in [4]. Later, with the help of the Killing vector field over a curve, the general helix was defined in 3D real space form, and in this space form, Lancret's theorem for general helices was given again by Barros [5]. Izumiya and Takeuchi named the curve whose main normal vector field makes a constant angle with a constant direction in 3D Euclidean space as a slant helix [6]. They also gave another characterization of the slant helix in [7]. Bükçü and Karacan, on the other hand, defined slant helixes in the Bishop frame and gave the necessary and sufficient condition for a curve to be a slant helix according to this frame as the ratio of Bishop curvatures of the curve being constant [8]. Another example of the classification of curves is the integral curves, which are the solution of a differential equation and define a parameterized curve. In [9,10,11,12], curves generated by the integral of the binormal vector field, which is one of the Frenet vectors of a curve given by any parameter s, are defined as associated curves.

    It is possible to generate new curves from a given curve by introducing geometric features, as in integral curves. There are some special curves in this context, including the Bertrand, Mannheim, Natural Mate, Smarandache, involute, evolute, and pedal curves, etc. In the references, there are some studies on these curves in different frames such as Frenet and the Bishop frame [13,14,15,16], and these curves have important applications in physics, engineering surface modeling, and computer graphics [17,18,19].

    In differential geometry, Smarandache curves are important in that they create more complex geometric structures by transitioning from one curve to another. Smarandache curves in E41 Minkowski space were introduced by Yilmaz and Turgut. By definition, Smarandache curves are included in Smarandache geometry, and if the position vector of a curve β is generated by the vectors of the Frenet frame of another curve α, then the curve β is called a Smarandache curve [20]. These curves enable in-depth analysis of the curve and surface. They are used in physics, engineering, biomechanics, robotics, and computer graphics, among other fields. Particularly in physics, they are employed in general relativity theory and space-time geometry [21]. They are used in materials science and structural analysis in engineering. They are essential to motion planning and object recognition in robotics and computer graphics [15]. They also contribute to theoretical and applied research in differential geometry by providing a more flexible and general framework than other types of curves. For example, Smarandache curves form a derived curve based on Frenet vectors since curvature and torsion are usually not constant compared to helical curves with constant curvature and constant torsion. While other curves based on curvature and torsion use only curvature and torsion, Smarandache curves directly use the other elements of the Frenet frame: the tangent, normal, and binormal vectors. Special Smarandache curves have been studied by some authors. Ali introduced special curves in Euclidean space, called Smarandache TN, NB, and TNB curves by Frenet-Serret vector fields [22]. Çetin et al. also studied Smarandache curves according to Bishop frame and made some calculations about the geometric properties of the curve [23]. Nurkan and Güven defined special curves by combining Smarandache curves and integral curves in the Frenet frame and gave some characterizations [24]. The Smarandache curves of Mannheim, Bertrand, involute and evolute curves are discussed in detail in [25,26,27,28], while their geometric properties in Minkowski space are explored in [29,30]. Recent advancements in curve and surface theories across various spaces include studies in Galilean space [31,32,33], and ruled surfaces generated from Smarandache curves are analyzed in [34,35,36].

    In this paper, new adjoint curves are defined by combining special Smarandache curves and integral curves in the Bishop frame, and interesting and useful results are provided. I define these new curves as tαζα1-Bishop adjoint curve, tαζα2-Bishop adjoint curve, ζα1ζα2-Bishop adjoint curve, and tαζα1ζα2-Bishop adjoint curve. Some relationships are established between a curve in the Bishop frame and the adjoint curves generated from it. Moreover, using these relations, I give necessary and sufficient conditions for the curve to be a general helix and slant helix.

    Some fundamental concepts related to differential geometry of space curves in Euclidean space E3 are reviewed in this section.

    Consider that Euclidean 3-space E3, with the standard flat metric given by

    .,.=dx21+dx22+dx23,

    where x1x3 is a rectangular coordinate system of E3. The norm is defined by

    u=|u,u|.

    A curve α is called a unit speed curve if its velocity vector α satisfies

    α=1.

    When α is a unit speed curve, its unit tangent vector is

    t(s)=α(s)

    and its curvature is

    κ=α(s).
    α(s)=κ(s)n(s)

    and

    b(s)=t(s)×n(s)

    give the principal normal vector and the unit binormal vector of α, respectively. Next, the well-known Frenet formula is shown as

    (tnb)=(0κ0κ0τ0τ0)(tnb), (2.1)

    where

    τ(s)=n(s),b(s)

    is the torsion of α.

    An alternate method for creating a moving frame that is well-defined even in cases when the curve's second derivative vanishes is the Bishop frame, also known as the parallel transport frame. To represent the parallel transport of an orthonormal frame along a curve, just parallel transport each frame component. Any convenient arbitrary basis and the tangent vector are used for the remaining section of the frame.

    Although t(s) for a given curve model is unique, the parallel transport frame is based on the observation that, for the remaining portion of the frame, I can choose any convenient arbitrary basis (ζ1(s),ζ2(s)) as long as it is in the normal plane perpendicular to t(s) at each point. Regardless of the curvature of the path, (ζ1(s),ζ2(s)) may change smoothly if their derivatives only depend on t(s) and not on each other. Thus, the various frame equations are available to us

    (tζ1ζ2)=(0k1k2k100k200)(tζ1ζ2). (2.2)

    The set {t,ζ1,ζ2} is referred to as a Bishop trihedron in this case, the curvatures k1 and k2 are called Bishop curvatures. The relation matrix can be expressed

    t=t,n=cosθ(s)ζ1+sinθ(s)ζ2,b=sinθ(s)ζ1+cosθ(s)ζ2, (2.3)

    where

    θ(s)=arctank2k1, k10, τ(s)=dθ(s)ds

    and

    κ(s)=k21+k22,

    so that k1 and k2 effectively correspond to a Cartesian coordinate system for the polar coordinates κ, θ with

    θ=τ(s)ds+θ0.

    The orientation of the parallel transport frame includes the arbitrary choice of integration constant which θ0, which disappears from τ (and hence from the Frenet frame) due to the differentiation (see [1,23]). Here, Bishop curvatures are defined by

    k1(s)=κ(s)cosθ(s), k2(s)=κ(s)sinθ(s) (2.4)

    on the other hand, if Eq (2.3) is regularized, the following equations are obtained

    t=t,ζ1=cosθ(s)nsinθ(s)b,ζ2=sinθ(s)n+cosθ(s)b. (2.5)

    When the angle between a curve's tangent lines and a fixed direction remains constant, the curve is called to general helix. The general helix's axis is the name given to this fixed direction. In 1802, Lancret articulated the definition of a helix, stating that a curve may be classified only as a general helix if the harmonic curvature or the ratio τκ remains constant, with

    κ0.

    If both

    κ0 and τ0

    are constants, the general helix is referred to as a circular helix [3].

    The constant geodesic curvature function of the principal image of the constant normal indicatrix characterizes a slant helix, as stated in [7]. This function that is constant is provided by

    σ(s)=(κ2(κ2+τ2)32(τκ)(s)).

    Bükçü and Karacan defined the concept of slant helix according to the Bishop frame in 3D Euclidean space E3 and stated that the necessary and sufficient condition for a curve α to be a slant helix is that the ratio of the Bishop's curvatures

    k10 and k20

    should be constant.

    Theorem 2.1. ([8]) Let the unit speed curve

    α:IE3

    be a slant helix with non-zero natural Bishop curvatures. Then α is slant helix if and only if k1k2 is constant.

    Definition 2.2. ([12]) Let α be an s-arc length parameterized regular curve with nonvanishing torsion and {Tα,Nα,Bα} is the Frenet frame of α. The adjoint curve of α is defined as

    β(s)=ss0Bα(u)du.

    Definition 2.3. ([22]) Let α be an s-arc length parameterized regular curve with nonvanishing torsion and {Tα,Nα,Bα} is the Frenet frame of α. Smarandache TN, NB, and TNB curves are defined by

    β=12(Tα+Nα),γ=12(Nα+Bα),μ=13(Tα+Nα+Bα),

    respectively.

    In [22], the author introduced that a curve in E3 parameterized by the arc length is called a Smarandache curve whose position vector is generated by the Frenet frame vectors on another regular curve. Then, in [24], the authors adapted this definition to regular curves as integrals of Smarandache curves in Euclidean 3-space. In this paper, New curves are obtained by taking the integrals of Smarandache curves with respect to the Bishop frame in Euclidean 3-space.

    Definition 3.1. Let α be an s-arc length parameterized regular curve with Bishop apparatus {tα,ζα1,ζα2,kα1,kα2}. tαζα1-Bishop adjoint curve, tαζα2-Bishop adjoint curve, ζα1ζα2-Bishop adjoint curve and tαζα1ζα2-Bishop adjoint curve of α are obtained

    β1(s)=12ss0(tα(s)+ζα1(s))ds, (3.1)
    β2(s)=12ss0(tα(s)+ζα2(s))ds, (3.2)
    β3(s)=12ss0(ζα1(s)+ζα2(s))ds, (3.3)
    β4(s)=13ss0(tα(s)+ζα1(s)+ζα2(s)) ds, (3.4)

    respectively.

    Remark 3.2. ([9]) Let α be a regular curve parameterized by arc length s, and let β1β4 be the adjoint curves of α. The arc length parameter s of these adjoint curves can be taken as s=s.

    Theorem 3.3. Let α be an s-arc length parameterized regular curve in E3 with Bishop apparatus {tα,ζα1,ζα2,kα1,kα2} and β1 be a tαζα1-Bishop adjoint curve of α. The Frenet vector fields, curvature and torsion of β1 are given by

    tβ11=12(tα+ζα1),nβ11=11+2h2(htα+hζα1+ζα2),bβ11=12+4h2(tαζα1+2hζα2)κβ1=12kα21+2h2,τβ1=12kα22h1+2h2, (3.5)

    where

    h=kτ1kα2.

    Proof. By differentiating Eq (3.1) and using Frenet formulas, I compute

    dβ1dsdsds=12(tα+ζα1),tβ11dsds=12(tα+ζα1), (3.6)

    if the norm of both sides of the Eq (3.6) is taken, (3.7) is obtained

    dsds=1, (3.7)

    also, Eq (3.8) is obtained from Eqs (3.6) and (3.7)

    tβ11=12(tα+ζα1), (3.8)

    differentiating (3.8) with respect to s and using Eq (2.2), I obtain

    tβ11=12(kα1ζα1+kα2ζα2kα1tα).

    Then, the curvature and principal normal vector field of the curve β1 are, respectively,

    κβ1=tβ11=122(kα1)2+(kα2)2

    and

    nβ11=12(kα1)2+(kα2)2(kα1tα+kα1ζα1+kα2ζα2),

    and besides this, I express

    tβ11×nβ11=12(tα+ζα1)×12(kα1)2+(kα2)2(kα1tα+kα1ζα1+kα2ζα2).

    Thus, the binormal vector of curve β1 is

    bβ11=14(kα1)2+2(kα2)2(kα2tαkα2ζα1+2kα1ζα2)

    to find the torsion of β1, differentiate nβ11 and use the relation

    τβ1=nβ11,bβ11.

    Then, I obtain

    τβ1=12kα22(kα1kα2)1+2(kα1kα2)2. (3.9)

    By ordering the expressions and assuming

    h=kα1kα2,

    I arrive at the final result.

    Theorem 3.4. Let α be an s-arc length parameterized regular curve in E3 with Bishop apparatus {tα,ζα1,ζα2,kα1,kα2} and β1 be a tαζα1-Bishop adjoint curve of α. The Bishop vector fields and curvatures of β1 are given by

    ζβ111=12+4h2[(2hcosθβ1+sinθβ1)tα+(2hcosθβ1+sinθβ1)ζα1+(2cosθβ1+2hsinθβ1)ζα2],ζβ112=12+4h2[(2hsinθβ1+cosθβ1)tα+(2hsinθβ1cosθβ1)ζα1+(2sinθβ1+2hcosθβ1)ζα2],kβ11=121+2h2cosθβ1kβ12=121+2h2sinθ. (3.10)

    Proof. If Eq (3.5) is substituted into Eqs (2.4) and (2.5), the proof is completed.

    Corollary 3.5. Let the unit speed curve

    α:IE3

    be a slant helix with respect to the Bishop frame, tαζα1-Bishop adjoint curve of α is a general helix.

    Proof. If I compute the quotient of the torsion and curvature of tαζα1-Bishop adjoint curve of α which are in Theorem 3.3, I have

    τβ1κβ1=12kα22h1+2h2 12kα21+2h2.

    Assuming that α is a slant helix, then h=0. Thus, I get

    τβ1κβ1=11+2h2,

    which means τβ1κβ1 is constant.

    Corollary 3.6. Let the unit speed curve

    α:IE3

    be a slant helix with the Bishop frame. If I rotate the Frenet frame around the tα axis, the angle of rotation is

    θβ1=12kα2ds.

    Proof. According to Bishop formulas,

    θβ1=τβ1ds

    is known. If the value of τβ1 is written as expressed in Eq (3.9), the following expression is obtained

    θβ1=(12kα2+2h1+2h2) ds,

    since α is a slant helix h=0. Therefore

    θβ1=12kα2ds.

    Theorem 3.7. Let α be an s-arc length parameterized regular curve in E3 with Bishop apparatus {tα,ζα1,ζα2,kα1,kα2} and β2 be a tαζα2-Bishop adjoint curve of α. The Frenet vector fields, curvature and torsion of β2 are given by

    tβ2=12(tα+ζα2),nβ2=11+2h2(htα+ζα1+hζα2),bβ2=12+4h2(tα2hζα1+ζα2),κβ2=12kα22+h2,τβ2=122kα1h2+h2. (3.11)

    Proof. By differentiating Eq (3.2) and using Frenet formulas, I compute

    β2(s)=12(tα+ζα2),tβ22(s)=12(tα+ζα2) (3.12)

    differentiating (3.12) with respect to s and using Eq (2.2), I obtain

    tβ22=12(kα1ζα1+kα2ζα2kα2tα).

    Then, the curvature and principal normal vector field of the curve β2 are, respectively,

    κβ2=tβ22=12(kα1)2+2(kα2)2

    and

    nβ22=1(kα1)2+2(kα2)2(kα2tα+kα1ζα1+kα2ζα2),

    beside this, I express

    tβ22×nβ22=12(tα+ζα2)×1(kα1)2+2(kα2)2(kα2tα+kα1ζα1+kα2ζα2).

    Thus, the binormal vector of curve β2 is

    bβ22=12(kα1)2+4(kα2)2(kα1tα2kα2ζα1+kα1ζα2),

    in order to find the torsion of β2, differentiating nβ2 and use the relation

    τβ2=nβ22,bβ22.

    Then, I have

    τβ2=122kα1(kα1kα2)2+(kα1kα2)2 (3.13)

    by ordering the expressions and assuming

    h=kα1kα2,

    I arrive at the final result.

    Theorem 3.8. Let α be an s-arc length parameterized regular curve in E3 with Bishop apparatus {tα,ζα1,ζα2,kα1,kα2} and β2 be a tαζα2-Bishop adjoint curve of α. The Bishop vector fields and curvatures of β2 are given by

    ζβ221=14+2h2[(2cosθβ2+hsinθβ2)tα+(2hcosθβ2+2sinθβ2)ζα1+(2cosθβ2hsinθβ2)ζα2],ζβ222=14+2h2[(2sinθβ2hcosθβ2)tα+(2sinθβ22cosθβ2)ζα1+(2sinθβ2+hcosθβ2)ζα2],kβ21=12kα22+h2cosθβ2, kβ22=12kα22+h2sinθβ2. (3.14)

    Proof. If Eq (3.11) is substituted into Eqs (2.4) and (2.5) the proof is completed.

    Corollary 3.9. Let the unit speed curve

    α:IE3

    be a slant helix with respect to the Bishop frame, then tαζα2-Bishop adjoint curve of α is a general helix.

    Proof. If I compute the quotient of the torsion and curvature of tαζα2-Bishop adjoint curve of α which are in Theorem 3.7. I have

    τβ2κβ2=122kα1h2+h2 12kα22+h2.

    Which means τβ2κβ2 is constant.

    Corollary 3.10. Let the unit speed curve

    α:IE3

    be a slant helix with the Bishop frame. If I rotate the Frenet frame around the tα axis, the angle of rotation is

    θβ2=122kα1ds.

    Proof. According to the Bishop formulas,

    θβ2=τβ2ds

    is known. If the value of τβ2 is written as expressed in Eq (3.13), the following expression is obtained

    θβ2=(122kα1+h2+h2) ds.

    Since α is a slant helix h=0. Therefore

    θβ2=122kα1ds.

    Theorem 3.11. Let α be an s-arc length parameterized regular curve in E3 with Bishop apparatus {tα,ζα1,ζα2,kα1,kα2} and β3 be a ζα1ζα2-Bishop adjoint curve of α. The Frenet vector fields, curvature and torsion of β3 are given by

    tβ33=12(ζα1+ζα2),nβ33=tα,bβ33=12(ζα1ζα2)κβ3=12kα2(1+h),τβ3=0. (3.15)

    Proof. By differentiating Eq (3.3) and using Frenet formulas, I compute

    β3(s)=12(ζα1+ζα2),tβ33(s)=12(ζα1+ζα2), (3.16)

    differentiating (3.16) with respect to s and using Eq (2.2), I obtain

    tβ33=12(kα1+kα2)tα.

    Then, the curvature and principal normal vector field of curve β3 are, respectively,

    κβ33=tβ33=12(kα1+kα2)

    and

    nβ33=tα,

    beside this, I express

    tβ33×nβ33=12(ζα1+ζα2)×tα.

    Thus, the binormal vector of curve β3 is

    bβ33=12( ζα1+ζα2),

    in order to find the torsion of β3, differentiating nβ33 and use the relation

    τβ3=nβ33,bβ33.

    Then, I obtain

    τβ3=0 (3.17)

    by ordering the expressions and assuming

    h=kα1kα2,

    I arrive at the final result.

    Theorem 3.12. Let be α an s-arc length parameterized regular curve in E3 with Bishop apparatus {tα,ζα1,ζα2,kα1,kα2} and β3 be a ζα1ζα2-Bishop adjoint curve of α. The Bishop vector fields and curvatures of β3 are given by

    ζβ31=cosθβ3tα+12sinθβ3ζα112sinθβ3ζα2,ζβ32=sinθβ3tα12cosθβ3ζα1+12cosθβ3ζα2,kβ31=12kα2(1+h)cosθβ3,kβ32=12kα2(1+h)sinθβ3. (3.18)

    Proof. If Eq (3.15) is substituted into Eqs (2.4) and (2.5) the proof is completed.

    Corollary 3.13. Let α be an s-arc length parameterized regular curve in E3 with Bishop frame. Then, the ζα1ζα2-Bishop adjoint curve of α is a slant helix.

    Proof. Let α be an s-arc length parameterized regular curve in E3 with Bishop frame. Using the Eq (3.18),

    kβ31kβ32=cotθβ3

    follows. From Bishop formulas and Eq (3.17),

    θβ3=c

    is obtained. Thus,

    θβ3=constant, 

    which means kβ31kβ32 is constant, so ζα1ζα2-Bishop adjoint curve of α is a slant helix.

    Corollary 3.14. Let the unit speed curve

    α:IE3

    be a slant helix according to Bishop frame. Then, ζα1ζα2-Bishop adjoint curve of α is involute of α.

    Proof. From Eq (3.15), I found that

    nβ33=tα,

    which means the tangent vector fields of α and ζα1ζα2-Bishop adjoint curve of α are perpendicular. Thus, the ζα1ζα2-Bishop adjoint curve is involute of α.

    Theorem 3.15. Let α be an s-arc length parameterized regular curve in E3 with Bishop apparatus {tα,ζα1,ζα2,kα1,kα2} and β4 be a tαζα1ζα2-Bishop adjoint curve of α. The Frenet vector fields, curvature and torsion of β4 are given by

    tβ44=13(tα+ζα1+ζα2),nβ44=121kα21+h+h2(kα2(1+h)tα+kα1ζα1+kα2ζα2),bβ44=161kα21+h+h2(kα2(1h)tαkα2(2+h)ζα1+kα2(1+2h)ζα2),κβ4=63kα21+h+h2,τβ4=323(kα2)2h1+h+h2+13kα2(h1). (3.19)

    Proof. The proof is similar to other Bishop adjoint curves.

    Theorem 3.16. Let α be an s-arc length parameterized regular curve in E3 with Bishop apparatus {tα,ζα1,ζα2,kα1,kα2} and β4 be a tαζα1ζα2-adjoint curve of α. The Bishop vector fields and curvatures of β4 are given by

    ζβ441=(kα2(1+h)cosθβ4+13kα2(1h)sinθβ4)tα+(kα1cosθβ4+13kα2(2+h)sinθβ4)ζα1+(kα2cosθβ413kα2(1+2h)sinθβ4)ζα22kα21+h+h2,ζβ442=(kα2(1+h)sinθβ4+13kα2(1h)cosθβ4)tα+(kα1sinθβ413kα2(2+h)cosθβ4)ζα1+(kα2sinθβ4+13kα2(1+2h)cosθβ4)ζα22kα21+h+h2,kβ41=63kα21+h+h2cosθβ4,kβ42=63kα21+h+h2sinθβ4.

    Proof. If Eq (3.19) is substituted into Eqs (2.4) and (2.5) the proof is completed.

    Corollary 3.17. Let the unit speed curve

    α:IE3

    be slant helix with respect to the Bishop frame, the β4 curve, which is the tαζα1ζα2-adjoint curve of α is a general helix.

    Proof. If I compute the quotient of the torsion and curvature of the tαζα1ζα2-Bishop adjoint curve of α as expressed in Theorem 3.15., I have

    τβ4κβ4=(h1)21+h+h2,

    which is constant.

    Corollary 3.18. Let the unit speed curve

    α:IE3

    be a slant helix with the Bishop frame. If I rotate the Frenet frame around the tα axis, the angle of rotation is

    θβ4=13kα2(h1)ds.

    Proof. According to the Bishop formulas,

    θβ4=τβ4ds

    is known. If the value of τβ4 is written as expressed in Eq (3.19), the following expression is obtained

    θβ4=(323(kα2)2h1+h+h2+13kα2(h1))ds,

    since α is a slant helix h=0. Thus

    θβ4=13kα2(h1)ds.

    Example 3.19. Consider the unit speed curve γ in E3

    γ(s)=12(cos(s),sin(s),3s),γ(s)=1.

    Bishop trihedron of γ were found in [37]. Now let's find tγζγ1, tγζγ2, ζγ1ζγ2, tγζγ1ζγ2-Bishop adjoint curves of γ. By using the definitions of these curves, I obtained, respectively;

    β1=12(12cos(s)+33sin(32s)cos(s)112sin(s)cos(32s),12sin(s)+33sin(s)sin(32s)+112cos(s)cos(32s),32s+12cos(s)),β2=12(12cos(s)33cos(s)cos(32s)112sin(s)sin(32s),12sin(s)33sin(s)cos(32s)+112sin(32s)cos(s),32s+12sin(s)),β3(s)=12(+33cos(s) sin(32s)112sin(s) cos(32s)33cos(s) cos(32s)112sin(s) sin(32s),33sin(s) sin(32s)+4cos(s) cos(32s)+7cos(s) sin(32s)33sin(s) cos(32s),12sin(s)+12cos(s)),β4(s)=12(12 cos(s)+33 cos(s) sin(32s)112 sin(s) cos(32s)+33 cos(s) cos(32s)112 sin(s) sin(32s),12 sin(s)+33 sin(s) sin(32s)+112 cos(s) cos(32s)33 sin(s) cos(32s)+112 cos(s) sin(32s),32s+12 sin(s)+12 cos(s)).

    The curve γ and its tγζγ1tγζγ2, ζγ1ζγ2, tγζγ1ζγ2-Bishop adjoint curves are shown in the following computer generated graphs, where Figure1 illustrates the tγζγ1-Bishop adjoint curve, Figure 2 the tγζγ2-Bishop adjoint curve, Figure 3 the ζγ1ζγ2-Bishop adjoint curve, Figure 4 the tγζγ1ζγ2-Bishop adjoint curves of γ, and Figure 5 combines γ and its Bishop adjoint curves into a single visualization for comparison.

    Figure 1.  tγζγ1-Bishop adjoint curve.
    Figure 2.  tγζγ2-Bishop adjoint curve.
    Figure 3.  ζγ1ζγ2-Bishop adjoint curve.
    Figure 4.  tγζγ1ζγ2-Bishop adjoint curve.
    Figure 5.  γ and its Bishop adjoint curves.

    General helices are often encountered in biology for DNA structures, in engineering for pipelines, in computer graphics for 3D modeling, and in robotics for motion planning within the scope of my findings.

    First, the adjoint curve β1 of the Smarandache curve tαζα1, which is generated from the Bishop vectors t and ζ1 of a unit-speed curve α in 3D Euclidean space, was determined. Upon analyzing the generated curve together with the main curve, it was found that when the curve α is a slant helix, the curve β1 is a general helix. In the second case, similarly, the adjoint curve β2 of the Smarandache curve tαζα2, generated from the Bishop vectors t and ζ2 of the curve α was determined. Upon analyzing the generated curve together with the main curve, it was found that when the curve α is a slant helix, the curve β2 is a general helix. In the third case, the adjoint curve β3 of the Smarandache curve ζ1ζ2, generated from the Bishop vectors ζ1 and ζ2 vectors of the curve α was determined. I found that the curve β3 is a slant helix and, at the same time, the involute of the curve α. In the fourth case, the adjoint curve β4 of the Smarandache curve tαζα1ζα2, generated from the Bishop vectors t, ζ1 and ζ2 of the curve α was determined. Upon analyzing the generated curve together with the main curve, it was found that when the curve α is a slant helix, the curve β4 is a general helix. In the final part of the study, adjoint curves of the Smarandache curves, generated from the Bishop vectors of the helix curve γ, were determined, and the shapes of these curves were plotted.

    My findings indicate that the adjoint of Smarandache curves, generated using the vectors of the Bishop frame, belongs to the class of general helices. Furthermore, the transition from special curves, such as slant helices, to general helices facilitates the analysis of various geometric structures of curves. Additionally, the relationship between the main curve and the new curves derived from it deepens our understanding of transformations of curves according to different frame systems.

    In this study, new curves were generated using the adjoint curves of Smarandache curves based on the vectors of the Bishop frame. These generated curves could contribute to surface theory by introducing new surfaces. With the proposed method, new curves and surfaces can be produced in different frames, enriching curve and surface theories with novel geometric structures.

    In this study, I construct new adjoint curves by combining special Smarandache curves and integral curves in Bishop frame. I call these new curves tαζα1-Bishop adjoint curve, tαζα2-Bishop adjoint curve, ζα1ζα2-Bishop adjoint curve, and tαζα1ζα2-Bishop adjoint curve. I establish some relations between a unit speed curve and its Bishop adjoint curves, and based on these relations, I provide an important characterization for a unit speed curve with respect to the Bishop frame.

    The author declares she has not used Artificial Intelligence (AI) tools in the creation of this article.

    The author would like to thank the referees for their valuable comments and suggestions, which contributed to the improvement of this article.

    The author declares no conflict of interest in this paper.

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