Topological ManifoldsMarzio De Corato
08 / Atlas of forms

Atlas of forms.

Surfaces, networks, waves and fractals. An explorable collection with explicit formulae and limitations.

The figures are grouped by subject so that, moving from a surface to a graph or a probabilistic representation, you can compare how geometry makes different relationships visible; each entry provides an observation guide, a formula and the limitations within which the model should be interpreted.

Three interactive experiments ↗

Security and interpretability

Graph theory and cyber-attacks

Graph theory and cyber-attacks
Unaffected nodeCompromised node

When devices, services and identities are described through their relationships, system security can be studied as a structural problem in which both a vulnerability and the paths through which it could expose other resources matter.

From connections to attack paths

A graph G = (V, E) consists of vertices V and edges E. In an asset network, vertices may represent devices or services, while edges describe connections, dependencies or trust relationships. An attack graph instead represents conditions, actions or system states, depending on the model, to examine how several steps can combine into a compromise.

G = (V, E)

The analogy with an epidemic helps illustrate how a compromise can spread between nodes, provided that the conditions for each transition are considered. Credentials, permissions, vulnerabilities and configurations determine which paths are feasible; a connection alone describes a possibility of communication.

How this supports defence

Path analysis helps identify the resources reachable from an initial position and the connections that form critical passages. Comparing the graph before and after a change shows how network segmentation, reduced privileges or a vulnerability fix can interrupt particular sequences. A node’s importance depends on its role and context, so its number of connections gives only a partial account of risk.

Reading this figure

Red nodes marked with a cross represent compromised systems in the scenario; green nodes remain unaffected, while pale pulses follow the propagation paths. The map provides a conventional geographical layout for an illustrative network whose links and timing are constructed to clarify the phenomenon. It does not show observed attacks or estimate compromise probabilities.

Probabilistic graph

Probabilistic graph

Variables occupy three lattice-like communities whose amber bridges make the connections between groups visible, while rotation helps distinguish those links from the dependencies within each community.

Formula, description and sources

Security and XAI

Observe the figure

Follow the amber bridges between communities, then change the viewing angle to distinguish the connections within each group. Small nodes identify variables; the underlying mesh makes the spatial arrangement easier to read.

Figure key

  • Green — connections within communities
  • Amber — inter-community connections and their endpoints
  • Pale — nodes representing variables

Formula or construction

P(s) = Z⁻¹ exp( ∑ᵢ hᵢsᵢ + ∑₍ᵢ,ⱼ₎∈E Jᵢⱼsᵢsⱼ )
sᵢ ∈ {−1, +1}
Relation in words

The probability of configuration s is the exponential of the sum of local h times s terms and J times paired-state interactions, divided by normalisation constant Z; each state is minus one or plus one.

How to read the model

The formula describes an Ising model on a graph. Z normalises the probabilities, while hᵢ and Jᵢⱼ control local terms and interactions. The three communities of 42 nodes each and their six bridges form an illustrative construction. Polyhedral placement, distances and colours support a reading of connectivity without assigning values to model parameters.

Execution paths

Execution paths

Program blocks form an architecture of directed paths in which a branch opens three alternatives that later merge. An amber route highlights one permitted sequence, with arrowheads indicating the direction of execution.

Formula, description and sources

Cybersecurity

Observe the figure

Start at the entry block and follow the arrowheads along the amber route. Compare it with the other two branches, observing where alternatives separate and where they merge on the way to the exit.

Figure key

  • Green — blocks and alternative paths
  • Amber — selected path, entry and exit

Formula or construction

G = (V, E)
Aᵢⱼ = 1 if there is an edge i → j, otherwise 0
Relation in words

Graph G contains vertices V and edges E; an adjacency-matrix entry is one when an edge connects vertex i to vertex j, and zero otherwise.

How to read the model

This illustrative execution graph contains ten blocks and eleven directed edges. Block positions and the highlighted route are design choices. The graph does not come from malware, and its adjacency matrix describes connectivity without assigning transition probabilities. Real program graphs may contain cycles, which this example omits.

Decision surface

Decision surface

The mesh follows a function that maps two variables to a value between zero and one. Three level curves reveal its shape, while the amber line marks the classification threshold, whose curvature depends on the interaction term xy.

Formula, description and sources

Artificial intelligence

Observe the figure

Observe the curvature of the mesh and follow the amber threshold, comparing it with the other two level curves. Change the orientation to distinguish function height from the positions of the two variables in the plane.

Figure key

  • Green — decision-function grid
  • Amber — threshold p = 0.5
  • Pale — level curves p = 0.2 and p = 0.8

Formula or construction

p(x,y) = 1 / (1 + exp[−(1.2x − 0.5y + 0.45xy)])
Classification boundary: p(x,y) = 0.5
Relation in words

Probability is one divided by one plus the exponential of the negative of one point two x minus zero point five y plus zero point four five x y; the displayed boundary corresponds to probability one half.

How to read the model

This analytical example uses the domain −2.1 ≤ x ≤ 2.1 and −1.7 ≤ y ≤ 1.7, with displayed height 2.5(p − 0.5). The level curves correspond to p = 0.2, p = 0.5 and p = 0.8; the central one is amber. The model is illustrative and has not been trained on data. Its geometry visualises a decision rule without establishing a causal explanation.

Open the experiment ↗
Regularity of a trace

Regularity of a trace

A continuous curve combines three values of the same time series at a fixed delay, giving recurring and irregular patterns a spatial form. Denser sampling and a tubular cross-section make the trajectory easier to follow where distinct portions overlap in projection.

Formula, description and sources

Cybersecurity and time series

Observe the figure

Follow the curve between its amber endpoints and compare portions that approach or move away from one another. Rotate the figure to distinguish projected crossings from the continuous trajectory in delay space.

Figure key

  • Green — curve in delay-coordinate space
  • Amber — start and end of the displayed curve
  • Pale — reference samples along the curve

Formula or construction

s(t) = sin(t) + 0.34 sin(3.3t) + 0.07 sin(19t)
v(t) = (s(t), s(t+τ), s(t+2τ)),  τ = 6·7π/179
SampEn(m,r) = −ln[A(m,r) / B(m,r)]
Relation in words

The signal s is the sum of three sinusoids. Vector v combines three values separated by delay tau, equal to six intervals on the original grid. Sample entropy is the negative natural logarithm of the ratio A to B, defined for dimension m and tolerance r.

How to read the model

The signal is a synthetic sum of sinusoids. The delay preserves the spacing of six samples on the original grid of 180 points from 0 to 7π. The 601 points render the same construction more continuously; coordinates are multiplied by 1.22 before graphical normalisation. Tube thickness and colours aid reading. SampEn introduces sample entropy: A and B count similar pairs of sequences of lengths m+1 and m, using the same matching convention and excluding self-matches. No SampEn value is estimated here.

Quantum and Post-Quantum Computing

Bloch sphere

Bloch sphere

A point on the sphere represents a pure state of a qubit, up to a global phase. The highlighted vector selects a state; meridians and parallels help read the two angular coordinates.

Formula, description and sources

Quantum computing

Observe the figure

Follow the amber arrow to the represented pure state and compare it with the angular arcs, meridians and parallels, distinguishing a change of viewpoint from a change in the quantum state.

Figure key

  • Amber — state vector and θ, φ arcs
  • Blue — sphere meridians
  • Green — sphere parallels
  • Pale — reference axes

Formula or construction

|ψ⟩ = cos(θ/2)|0⟩ + exp(iφ) sin(θ/2)|1⟩
r = (sinθ cosφ, sinθ sinφ, cosθ)
Relation in words

The state is cosine of half theta times state zero plus the exponential of i phi times sine of half theta times state one; the vector coordinates are sine theta cosine phi, sine theta sine phi, and cosine theta.

How to read the model

Rotating the viewer changes the viewpoint; it does not apply a gate to the qubit. Mixed states occupy the interior of the sphere. This representation does not describe an arbitrary multi-qubit state.

Open the experiment ↗
Wave superposition

Wave superposition

Peaks and troughs result from the sum of two periodic contributions. The figure introduces superposition visually, while the second relation shows the cross term responsible for interference between complex amplitudes.

Formula, description and sources

Quantum computing

Observe the figure

Compare crests and troughs using the surface grid and follow the two central sections, which reveal the superposition of periodic contributions as you change viewpoint on this single field configuration.

Figure key

  • Green — grid of the resulting field
  • Amber — section y = 0
  • Pale — section x = 0

Formula or construction

f(x,y) = 0.34[cos(3x) + cos(3y)]
|ψ₁ + ψ₂|² = |ψ₁|² + |ψ₂|² + 2 Re(ψ₁*ψ₂)
Relation in words

The surface sums cosine of three x and cosine of three y, multiplied by zero point three four; the squared magnitude of two summed amplitudes includes their individual squared magnitudes and twice the real part of the first conjugated amplitude times the second.

How to read the model

The surface is a snapshot of a synthetic real-valued field. It is not a probability density and is not normalised as a wave function. The viewer rotates the scene without simulating time evolution.

Open the experiment ↗
Circuit for a Bell state

Circuit for a Bell state

Two lines represent the qubits. A Hadamard transformation on the first, followed by a controlled-X gate, prepares a Bell state from |00⟩. The terminal shapes suggest the circuit’s readout points.

Formula, description and sources

Quantum computing

Observe the figure

Follow the two lines from left to right, identifying the Hadamard block on the first qubit and the amber link between the control and target of the X gate before the terminal readout symbols; the formula specifies the operation sequence.

Figure key

  • Blue — two circuit wires
  • Green — H block and terminal readout boxes
  • Amber — control, X target and terminal indicators

Formula or construction

|00⟩ → (H ⊗ I)|00⟩ → CNOT(H ⊗ I)|00⟩
|Φ⁺⟩ = (|00⟩ + |11⟩) / √2
Relation in words

Apply Hadamard to the first qubit and identity to the second in state zero zero, followed by CNOT; the result is the sum of states zero zero and one one, divided by the square root of two.

How to read the model

This is a schematic representation of the circuit, not a measurement simulator or physical device. Internal labels are omitted to keep the geometry readable; the sequence of operations is specified in the formula.

Lattice and basis

Lattice and basis

Integer combinations of three vectors generate the lattice points. Highlighted segments distinguish the basis from the point network, providing an initial visual reference for lattice problems.

Formula, description and sources

Post-quantum computing

Observe the figure

Identify the three basis arrows and the highlighted parallelepiped, then follow the translations that generate neighbouring points, rotating the figure to separate directions that overlap in projection.

Figure key

  • Pale — lattice points
  • Blue — connections between neighbouring points
  • Green — edges of the selected cell
  • Amber — three basis vectors

Formula or construction

Λ(B) = {n₁b₁ + n₂b₂ + n₃b₃ : n₁,n₂,n₃ ∈ ℤ}
Relation in words

The lattice is the set of all combinations of the three basis vectors with integer coefficients.

How to read the model

The model has three dimensions and finitely many points. It does not represent the dimensions, parameters or full structure of ML-KEM, nor every approach to post-quantum cryptography. The source concerns the cryptographic context, not this illustrative lattice.

Quantitative methods

Stochastic paths

Stochastic paths

The curves represent twelve synthetic realisations of geometric Brownian motion. Each path is generated from random increments; a shared component introduces dependence between realisations.

Formula, description and sources

Quantitative finance

Observe the figure

Follow the amber path and compare it with the other eleven, observing sample changes without assigning economic meaning to the lateral spacing; the piecewise-linear trace preserves the increments of the synthetic construction.

Figure key

  • Blue — path ensemble, shaded from blue to green
  • Amber — one realisation selected as a reference
  • Pale — final endpoints of the other paths

Formula or construction

dSₜ = μSₜ dt + σSₜ dWₜ
Sₜ = S₀ exp[(μ − σ²/2)t + σWₜ]
Relation in words

The change in S contains drift mu S times dt and a random term sigma S times dW; the solution multiplies the initial value by the exponential of mu minus half sigma squared, times t, plus sigma W.

How to read the model

S₀ = 1, μ = 0.07 and σ = 0.32, with a fixed random seed. The coefficient of the shared component in the increments is 0.55, so the theoretical correlation between increments of different paths is 0.55². Lateral spacing distinguishes the curves; it is not an economic variable. These are neither market data nor forecasts.

Gaussian density

Gaussian density

The surface describes a bivariate normal density. Correlation tilts the bell’s cross-sections: observing its shape helps distinguish dispersion from dependence between the two components.

Formula, description and sources

Quantitative methods

Observe the figure

Compare the elliptical sections, which follow constant density levels, and switch between top and side views to recognise both the orientation of dispersion and the changing height.

Figure key

  • Blue — density grid
  • Pale — three constant-density ellipses
  • Amber — fourth ellipse, selected as a reference

Formula or construction

f(x) = exp[−½(x−μ)ᵀΣ⁻¹(x−μ)] / (2π√detΣ)
μ = (0,0),  Σ = [[1,0.55],[0.55,1]]
Relation in words

The Gaussian density exponent is minus one half of the quadratic form of the deviation from the mean with the inverse covariance; normalisation is two pi times the square root of the determinant of sigma.

How to read the model

The height is rescaled as 9f − 0.7 for display. This is a theoretical distribution with stated parameters, not an estimate obtained from observations.

Covariance ellipsoid

Covariance ellipsoid

The ellipsoid translates a covariance matrix into spatial directions and magnitudes. The highlighted section and principal axes reveal anisotropy by showing how dispersion varies with direction.

Formula, description and sources

Quantitative finance

Observe the figure

Compare the ellipsoid grid with its three principal directions, determined by the covariance matrix, and follow the amber section while rotating the figure to distinguish semiaxis lengths from their screen projection.

Figure key

  • Green — ellipsoid grid
  • Pale — two principal directions
  • Amber — direction of greatest dispersion and reference section

Formula or construction

(x−μ)ᵀΣ⁻¹(x−μ) = 1
Σ = TTᵀ,  T = [[1.6,0.5,0.1],[0,0.85,0.24],[0,0,0.65]]
Relation in words

The surface contains points whose quadratic form of deviation from the mean, using inverse covariance, equals one; covariance is matrix T times its transpose.

How to read the model

The displayed level corresponds to a Mahalanobis distance of one. It does not automatically represent a 95% confidence region or a portfolio efficient frontier. The matrix is synthetic and positive definite.

Carbon, surfaces and topology

Gyroid

Gyroid

Passages and openings connect the surface in all three spatial directions. This form evokes the study of periodic structures and materials whose internal geometry influences their properties.

Formula, description and sources

Physics and geometry

Observe the figure

Follow the illuminated sections around the channels as rotation reveals passages between regions that overlap in projection; amber identifies one reference section of the same nodal construction.

Figure key

  • Green — sections at constant x and z
  • Blue — sections at constant y
  • Amber — reference section z = 0

Formula or construction

sin(x)cos(y) + sin(y)cos(z) + sin(z)cos(x) = 0
Relation in words

The sum of sine x times cosine y, sine y times cosine z, and sine z times cosine x equals zero.

How to read the model

The formula generates a nodal approximation to the minimal surface, not the exact gyroid. The model shows a bounded portion of the domain and contains no atoms or chemical bonds.

Schwarz P surface

Schwarz P surface

The surface separates space into two regions connected through periodic openings. Its symmetry and curvature offer a useful reference for understanding three-dimensional networks and porous structures.

Formula, description and sources

Physics and topology

Observe the figure

Compare the openings along the three directions with the illuminated sections, following how the surface joins neighbouring necks as the moving light distinguishes the near side from the interior.

Figure key

  • Green — sections at constant x and z
  • Blue — sections at constant y
  • Amber — reference section z = 0

Formula or construction

cos(x) + cos(y) + cos(z) = 0
Relation in words

The sum of the cosines of coordinates x, y and z equals zero.

How to read the model

This is a nodal representation of Schwarz P on a finite domain, not an exact numerical solution of the zero-mean-curvature condition. The surface should not be confused with an atomistic schwarzite.

Schwarz D surface

Schwarz D surface

The spatial network has connections and openings distinct from those of Schwarz P. Rotating it helps trace the passages and distinguish the regions separated by the surface.

Formula, description and sources

Physics and topology

Observe the figure

Follow the surface sections and rotate the figure to separate branches that overlap in the initial view, comparing constrictions and openings within the displayed nodal patch.

Figure key

  • Green — sections at constant x and z
  • Blue — sections at constant y
  • Amber — reference section z = 0

Formula or construction

cos(x)cos(y)cos(z) − sin(x)sin(y)sin(z) = 0
Relation in words

The product of the cosines of x, y and z minus the product of their sines equals zero.

How to read the model

This periodic equation is a nodal representation of the D family, with a suitable choice of origin. It is not a relaxed atomic structure. Tiny isolated fragments caused by cutting the domain boundary are excluded.

P688 schwarzite

P688 schwarzite

The carbon lattice's hexagons remain visible as the framework curves around its openings. Octagons connect the saddle regions, where the bonds reveal the narrowing and subsequent widening of the structure.

Formula, description and sources

Carbon and negative curvature

Observe the figure

Follow the six-atom rings along the curved walls and identify the octagons connecting them through the neck. Rotate the lattice to follow repeating cavities in all three spatial directions, with hexagons outlining their curved walls and necks connecting adjacent cells. “Two curvatures” shows a blue axial section and an amber transverse section; at the pale point, they follow principal directions and bend in opposite senses. “P688 structure” broadens the view to the network of connected cavities.

Figure key

  • Green — carbon–carbon bonds
  • Pale — atoms at lattice vertices

Formula or construction

cos(2πx) + cos(2πy) + cos(2πz) = 0
K = k₁ · k₂ < 0 in the displayed neck.
P688: cubic Im-3m cell, a = 7.828 Å, 48 atoms per cell.
Relation in words

The sum of the cosines of two pi times each coordinate is zero. Gaussian curvature K is the product of the principal curvatures k one and k two. Their opposite signs make the product negative in the neck.

How to read the model

The carbon positions follow the P688 crystallographic site (0.31952, 0.31952, 0.09373) and Im-3m symmetries; bonds join nearest neighbours at 1.452–1.467 Å. The initial view contains eight cells arranged 2×2×2, with 384 atoms, 64 complete hexagons and 48 complete octagons. The overview extends the periodic structure to 27 cells arranged 3×3×3, with 1,296 atoms. The finite boundaries cut rings and bonds that would continue through the periodic lattice. Dark ring faces distinguish front and rear bonds; they do not represent physical walls. The continuous surface appears in “Two curvatures” as a nodal guide for the Schwarz P family; its mean curvature can differ from zero, unlike the exact minimal surface. The carbon lattice and the reference surface are distinct descriptions. Colours, lighting and small offsets of the guide curves support legibility; carbon coordinates preserve the published model's distances, apart from uniform display scaling. This is a theoretical structure, with no new energy minimisation.

Out-of-plane deformation

Out-of-plane deformation

The ideal lattice is displaced out of its plane according to a regular field. One can observe how deformation changes the ribbon’s shape while leaving lattice connectivity recognisable.

Formula, description and sources

Carbon nanostructures

Observe the figure

Follow the hexagons along the sheet as the out-of-plane deformation changes their projection while preserving connectivity; small blue and amber vertices distinguish the sign of the synthetic displacement, and the bonds keep the lattice readable.

Figure key

  • Green — lattice connections
  • Blue — vertices with positive z displacement
  • Amber — vertices with zero or negative z displacement

Formula or construction

uᶻ(x,y) = 1.1 sin(0.7x) cos(0.42y)
Relation in words

Displacement along z equals one point one times the sine of zero point seven x times the cosine of zero point four two y.

How to read the model

The field is synthetic. It is not a normal mode calculated from a dynamical matrix, does not reproduce a Raman frequency and is not an ab initio result by the author. The figure deliberately distinguishes geometric deformation from physical vibrational analysis.

Negatively curved connections

Negatively curved connections

Longitudinal curves and circular sections describe three families of necks. The model highlights transitions between regions and the role of curvature in spatial connections.

Formula, description and sources

Nanostructure geometry

Observe the figure

Compare the three curve families, which distinguish necks along different axes, and, starting at the amber throat rings, follow the longitudinal curves towards the wider sections, rotating the figure to separate overlapping projections.

Figure key

  • Green — neck family along z
  • Blue — neck family along x
  • Pale — neck family along y
  • Amber — narrowest sections of the three necks

Formula or construction

r(u,v) = (0.64 cosh(v)cos(u), 0.64 cosh(v)sin(u), v)
Three families of necks, oriented along different axes.
Relation in words

The first two coordinates describe a circle with radius zero point six four times the hyperbolic cosine of v, while the third coordinate is v; necks are oriented along three directions.

How to read the model

This geometric construction consists of hyperbolic necks scaled along the axes. It is not an atomistic model of a schwarzite: it encodes neither carbon coordination, stability nor bond lengths. The source documents the scientific relationship between topology and negatively curved carbon.

C₆₀ fullerene

C₆₀ fullerene

Twelve pentagons allow a hexagonal carbon network to close into a cage, revealing how ring arrangement accompanies the curvature of a closed carbon surface.

Formula, description and sources

Carbon cages and positive curvature

Observe the figure

Follow a pentagon and compare its boundary with neighbouring hexagons. Rotate the cage to trace the continuous network and the three bonds meeting at each atom. Compare this convex cage with the periodic saddle openings of the schwarzite.

Figure key

  • Green — cage bonds
  • Pale — carbon atoms
  • Warm tone — pentagonal faces

Formula or construction

V = 60, E = 90, F = 32
12 pentagons + 20 hexagons
V − E + F = 2; three neighbours per vertex.
Relation in words

Sixty vertices and ninety edges enclose thirty-two faces: twelve pentagons and twenty hexagons. Vertices minus edges plus faces equals two.

How to read the model

This is an ideal truncated icosahedron with equal bond lengths; molecular C₆₀ has different bond lengths. Dark faces clarify depth and pentagons have a warmer tint. The cage introduces fullerenes. The linked work on two C₂₈ clathrates concerns distinct crystalline structures, whose reconstruction requires specific coordinates.

Graphene nanoribbons

Graphene nanoribbons

Cutting a graphene sheet leaves an atomic edge whose properties can be investigated through spectroscopy and calculations. The two views make armchair and zigzag terminations recognisable.

Formula, description and sources

Atomic edges and vibrational signatures

Observe the figure

Observe the atom pairs along the armchair edge, then select the zigzag view to compare its different boundary pattern. Follow the hexagons inward and examine the ends of the finite fragment.

Figure key

  • Green — nanoribbon bonds
  • Pale — carbon atoms

Formula or construction

Honeycomb lattice: two atoms per primitive cell.
Nearest neighbours: dᵢⱼ = 1 in model units.
Armchair and zigzag: two orientations of the same lattice.
Relation in words

The planar lattice has two atoms per primitive cell and unit bond lengths in this model. The cut direction determines an armchair or zigzag termination.

How to read the model

The finite fragments contain 80 and 84 carbon atoms respectively. Coordinates describe an ideal planar lattice; hydrogen and other terminating groups are omitted. The fragments have different finite dimensions and illustrate edge patterns. The linked Raman and HREELS papers examine specific structures through measurements and calculations. These figures introduce their geometry; peak assignments and frequencies belong to the papers’ experimental and theoretical results.

Deformed nanoribbon

Deformed nanoribbon

Twisting moves the hexagons out of plane and changes the orientation of ribbon regions, providing a visual introduction to the relationship between structural distortion and electronic properties.

Formula, description and sources

Lattice shape and electronic structure

Observe the figure

Follow an edge from one end to the other as it turns around the long axis. Compare central rings with those at the ends and rotate the model to distinguish the imposed twist from perspective.

Figure key

  • Green — deformed ribbon bonds
  • Pale — carbon atoms

Formula or construction

R(x,y) = (x, y cos θ(x), y sin θ(x))
θ(x) = 0.16 x
The planar ribbon’s connectivity is preserved.
Relation in words

Each transverse coordinate rotates through an angle that increases linearly along the ribbon axis. The bond list remains identical to the planar ribbon.

How to read the model

This illustrative geometric deformation acts on 80 atoms. It preserves connectivity while changing some distances and bond angles. Its twist parameter is chosen for visual clarity. The 2018 paper examines specific ribbons and control of structural distortion; this figure introduces the question without claiming an optimised structure, a calculated bandgap or a normal vibrational mode.

Bilayer graphene nanoflakes

Bilayer graphene nanoflakes

Two overlapping graphene fragments reveal how a relative shift changes ring alignment, introducing the role of interlayer interactions in the study of optical properties.

Formula, description and sources

Stacking and optical properties

Observe the figure

Rotate the model to separate the two planes visually, then switch between shifted and aligned layers. Rings remain identical within each fragment while the relative positions of facing atoms change.

Figure key

  • Green — bonds in one fragment
  • Blue — bonds in the other fragment
  • Pale — atoms in both layers

Formula or construction

R₂ = R₁ + (Δx, 0, h)
h = 2.36 dCC; Δx = 1 dCC or 0
Two separate graphs, with no interlayer covalent bonds.
Relation in words

The second fragment is translated horizontally and separated vertically from the first. All drawn bonds belong to individual layers.

How to read the model

Two ideal 40-carbon fragments have a fixed separation and an illustrative relative shift. Hydrogen, functional groups and orbitals are omitted. Colours distinguish the layers. Aligned and shifted views preserve each fragment’s geometry. The linked paper derives optical results from calculations on specific systems; this figure depicts arrangement and overlap without simulating absorption or charge transfer.

Geometry and fractals

Julia set

Julia set

Iterating the same rule produces intricate boundaries between escaping points and points that remain bounded. Colour depends on escape time and reveals details at different scales.

Formula, description and sources

Fractals and dynamical systems

Observe the figure

The initial view presents the plane frontally, so you can examine boundaries and escape-time variations without tilt obscuring the details; the representation retains the 180-iteration limit and the available resolution.

Figure key

  • Green — light and dark bands: periodic escape-time colouring without a monotonic colour scale

Formula or construction

zₙ₊₁ = zₙ² + c
c = −0.74543 + 0.11301i
Relation in words

At each iteration, square complex number z and add c, equal to minus zero point seven four five four three plus zero point one one three zero one times the imaginary unit.

How to read the model

The fractal is planar. The viewer allows its plane to be oriented in space without inventing a three-dimensional volume. The image uses 180 iterations: it is a finite approximation, not a representation of every mathematical detail.

Sierpiński tetrahedron

Sierpiński tetrahedron

Four scaled-down copies occupy a tetrahedron’s vertices. Repeating the construction produces a structure in which empty space is as recognisably organised as the solids.

Formula, description and sources

Fractals

Observe the figure

Follow the illuminated tetrahedral edges and compare openings at different construction levels, rotating the figure to distinguish internal gaps from overlaps introduced by a single projection.

Figure key

  • Green — tetrahedron edges
  • Dark — solid faces, distinct from the cavities

Formula or construction

S = ⋃ᵢ₌₁⁴ fᵢ(S),  fᵢ(x) = (x + vᵢ)/2
Self-similar dimension: log(4)/log(2) = 2
Relation in words

The set is the union of four copies obtained by halving the sum of a point and each vertex; the self-similar dimension is logarithm of four divided by logarithm of two, equal to two.

How to read the model

The scene shows three recursion levels, hence 64 tetrahedra. The stated dimension concerns the mathematical limit, not the finite rendered object.

Menger sponge

Menger sponge

Dividing a cube into 27 parts and removing seven generates a structure of interconnected cavities. Recursion reproduces this arrangement at progressively smaller scales.

Formula, description and sources

Fractals

Observe the figure

Look through the larger openings and follow the edges of smaller cavities as rotation reveals internal passages; shared faces between adjacent cubes are omitted from the rendering to clarify the same 400-cell structure.

Figure key

  • Green — outer and cavity edges
  • Dark — exposed cube faces

Formula or construction

M = ⋃ᵢ₌₁²⁰ fᵢ(M),  scale ratio = 1/3
Self-similar dimension: log(20)/log(3)
Relation in words

The set is the union of twenty copies scaled to one third; its self-similar dimension is logarithm of twenty divided by logarithm of three.

How to read the model

Two levels are displayed, corresponding to 400 cubes. Properties of the infinite limit should not be attributed indiscriminately to this finite model.

Möbius strip

Möbius strip

A half-twist before joining the ends changes the relationship between boundary and surface. Following the strip explores a form in which a local distinction between two sides cannot be extended to a global choice.

Formula, description and sources

Topology and form

Observe the figure

Follow the amber boundary until you return to the starting point, observing how one continuous path visits both apparent margins while the grid reveals the half-twist of the surface.

Figure key

  • Green — surface grid
  • Amber — single continuous ribbon boundary

Formula or construction

r(u,v) = ((1+0.35v cos(u/2))cos(u),
          (1+0.35v cos(u/2))sin(u), 0.35v sin(u/2))
0 ≤ u ≤ 2π,  −1 ≤ v ≤ 1
Relation in words

Parameter u makes a full turn while v ranges from minus one to one; the width, scaled by zero point three five, makes a half turn around the central circle.

How to read the model

The formula parametrises a Möbius strip. The connection with bodily movement is personal and geometric; it does not attribute topological properties or therapeutic effects to yoga practice.

Helicoid

Helicoid

A straight line rotates while advancing along an axis, generating a ruled surface. The relationship between rotation and translation reveals the continuity of the form from different viewpoints.

Formula, description and sources

Calculus and differential geometry

Observe the figure

Follow the amber boundaries and compare them with the straight rulings of the grid, observing how rotation around the axis accompanies vertical translation in the surface construction.

Figure key

  • Green — grid and straight rulings
  • Amber — two outer helical boundaries

Formula or construction

r(u,v) = (u cos(v), u sin(v), 0.23v)
Relation in words

The first two coordinates are u cosine v and u sine v, while height is zero point two three v, coupling rotation with vertical translation.

How to read the model

This is a finite portion of a parametric helicoid. Rotating the viewer moves the camera; it does not change the pitch of the surface.

Catenoid

Catenoid

Rotating a catenary generates a surface with a central neck. The contrast between the two principal curvatures makes visible a geometry encountered in the study of minimal surfaces.

Formula, description and sources

Differential geometry

Observe the figure

Compare the amber throat ring with the wider sections and follow the longitudinal curves, rotating the surface to see the profile curvature alongside the curvature of circular sections.

Figure key

  • Green — meridians and circular sections
  • Amber — narrowest circumference at the neck

Formula or construction

r(u,v) = (0.8 cosh(v)cos(u),
          0.8 cosh(v)sin(u), 0.8v)
Relation in words

At height zero point eight v, the circular section has radius zero point eight times the hyperbolic cosine of v; angle u runs around the circle.

How to read the model

This is a parametric portion of a catenoid, discretised for display. The construction does not simulate the stability of a soap film or a physical experiment.

Torus

Torus

Two periodic coordinates traverse the surface in distinct directions. The central hole and the continuity of paths make it a useful form for considering periodicity and topology.

Formula, description and sources

Geometry and periodicity

Observe the figure

Follow the amber cycle around the ring and compare it with the pale section around the tube, using the grid to distinguish the two periodic directions even when part of the surface is hidden behind the central opening.

Figure key

  • Green — surface grid
  • Amber — cycle around the ring
  • Pale — cycle around the tube

Formula or construction

r(u,v) = ((R+r cos(v))cos(u),
          (R+r cos(v))sin(u), r sin(v))
R = 1,  r = 0.38
Relation in words

A circle of radius zero point three eight revolves around the central axis at distance one; u locates a point around the ring and v around the tube section.

How to read the model

The torus is a parametric geometric object here. It does not automatically represent a state space or any particular material structure.

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Graph theory and cyber-attacks

Unaffected nodeCompromised node

When devices, services and identities are described through their relationships, system security can be studied as a structural problem in which both a vulnerability and the paths through which it could expose other resources matter.

From connections to attack paths

A graph G = (V, E) consists of vertices V and edges E. In an asset network, vertices may represent devices or services, while edges describe connections, dependencies or trust relationships. An attack graph instead represents conditions, actions or system states, depending on the model, to examine how several steps can combine into a compromise.

G = (V, E)

The analogy with an epidemic helps illustrate how a compromise can spread between nodes, provided that the conditions for each transition are considered. Credentials, permissions, vulnerabilities and configurations determine which paths are feasible; a connection alone describes a possibility of communication.

How this supports defence

Path analysis helps identify the resources reachable from an initial position and the connections that form critical passages. Comparing the graph before and after a change shows how network segmentation, reduced privileges or a vulnerability fix can interrupt particular sequences. A node’s importance depends on its role and context, so its number of connections gives only a partial account of risk.

Reading this figure

Red nodes marked with a cross represent compromised systems in the scenario; green nodes remain unaffected, while pale pulses follow the propagation paths. The map provides a conventional geographical layout for an illustrative network whose links and timing are constructed to clarify the phenomenon. It does not show observed attacks or estimate compromise probabilities.

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Topological Manifolds

Scientific formulas

Relations, assumptions and study references. These are not empirical results from the author’s research.

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