Database
Browse 6,168 skills across 448 packs and 38 categories
Travel Tech Apps
60LHelps travelers build a focused digital toolkit for every trip phase. Covers booking platform strategy, offline navigation, connectivity planning, expense tracking, and leveraging technology to reduce friction without replacing the experience of travel itself.
Travel Writing
114LTravel writing specialist covering narrative storytelling, destination guides, reviews, and adventure narratives. Focuses on sensory detail, authentic voice, avoiding clichés, and understanding publication markets from Condé Nast Traveler to travel blogs.
Ancient Civilizations
81LAncient civilizations specialist covering Mesopotamia, Egypt, Greece, Rome, Indus Valley, China, and Mesoamerica. Provides expert analysis of government systems, daily life, technology, art, religion, trade networks, rise and fall patterns, archaeological evidence, and primary sources.
Archaeological Methods
60LArchaeological methods specialist guiding excavation technique, survey and prospection, dating methods, artifact analysis, bioarchaeology, spatial analysis, ethnoarchaeology, cultural resource management, and the ethics of archaeological practice including repatriation and community engagement.
Art History Visual Culture
61LArt history and visual culture specialist guiding analysis of artistic movements from antiquity to the contemporary, iconography, patronage systems, museum studies, material culture, visual propaganda, the global art market, and critical approaches including feminist and post-colonial art history.
Colonial Postcolonial History
60LColonial and post-colonial history specialist guiding analysis of European imperialism, settler colonialism, decolonization movements, neo-colonialism, subaltern studies, the legacy of empire in contemporary politics, and the recovery of colonized peoples' histories on their own terms.
Cultural Heritage Preservation
80LCultural heritage preservation specialist covering UNESCO World Heritage, tangible and intangible heritage, preservation techniques, documentation methods, digital preservation, repatriation debates, community-based preservation, heritage tourism management, and archival practices.
Digital Humanities
61LDigital humanities and historical data specialist guiding text mining, GIS mapping, network analysis, database design for historical research, digital archives, computational text analysis, data visualization, and the methodological challenges of applying computational methods to humanistic inquiry.
Diplomatic History
61LDiplomatic history specialist guiding analysis of international relations from ancient treaty systems through modern multilateral diplomacy, alliance formation, peace negotiations, the history of international law, intelligence and espionage, the evolution of the state system, and the role of non-state actors in international affairs.
Economic History
60LEconomic history analyst guiding study of trade systems, industrialization, monetary history, labor movements, capitalism and its alternatives, financial crises, development economics in historical perspective, and the quantitative and qualitative methods used to study economic change over time.
Environmental History
61LEnvironmental history specialist guiding analysis of human-nature interactions across time, climate history, deforestation and land use change, water management, disease ecology, conservation movements, environmental justice, energy transitions, and the deep historical roots of the Anthropocene.
Genealogy Family History
84LGenealogy and family history research specialist covering DNA testing interpretation, census records, immigration records, vital records, church records, newspaper archives, military records, land records, oral history collection, organizing findings, and common brick walls and solutions.
History of Science
71LHistory of science and technology specialist covering the Scientific Revolution, key discoveries and inventions, paradigm shifts, the scientific method's evolution, science and society, technology transfer, women and minorities in science history, and science funding and institutions.
Legal Constitutional History
61LLegal and constitutional history specialist guiding analysis of legal systems from ancient codes through modern constitutionalism, common law and civil law traditions, human rights history, landmark court cases, the rule of law, legal pluralism, and the relationship between law, power, and social change.
Maritime History
61LMaritime history specialist guiding analysis of seafaring civilizations, naval architecture, oceanic exploration, port cities and maritime trade networks, piracy, maritime law, underwater archaeology, the social history of sailors, and the role of the sea in shaping human civilization across every ocean and period.
Medieval History
80LMedieval history specialist covering feudalism, the Crusades, the Black Death, Byzantine Empire, Islamic Golden Age, Viking Age, Mongol Empire, medieval technology, castle architecture, monastic life, trade guilds, and the transition to the Renaissance.
Military History
80LMilitary history specialist covering major battles and campaigns, the evolution of military strategy from ancient phalanx to modern warfare, weapons technology, logistics, intelligence, famous commanders, guerrilla warfare, naval warfare, air power, and the evolution of military doctrine.
Modern World History
83LModern world history specialist covering 1500 to the present. Addresses the Age of Exploration, colonialism, Industrial Revolution, World Wars, Cold War, decolonization, globalization, and the digital revolution with emphasis on interconnections and multiple perspectives.
Oral History
81LOral history collection and preservation specialist covering interview techniques, equipment selection, question design, ethical considerations including informed consent and community ownership, transcription methods, archival standards, digital preservation, community oral history projects, and Indigenous oral traditions.
Religious History
61LReligious history specialist guiding analysis of the origins and development of world religions, theology in historical context, religion and politics, mysticism and popular piety, interfaith encounters, religious violence and tolerance, secularization debates, and the academic study of religion as a critical historical discipline.
Renaissance Enlightenment History
61LRenaissance and Enlightenment historian guiding analysis of the cultural transformations of fourteenth- through eighteenth-century Europe, the Scientific Revolution, the Age of Reason, political philosophy, humanism, the Reformation, and the intellectual foundations of modernity in their full complexity and global context.
Womens History Gender Studies
61LWomen's history and gender studies specialist guiding analysis of feminist movements, gendered labor, reproductive rights, women in politics and war, masculinity studies, LGBTQ+ history, intersectionality, and the recovery of women's voices and experiences from historical records shaped by patriarchal assumptions.
Abstract Algebra
111LTriggers when users need help with abstract algebra. Activate for questions about groups, rings, fields, homomorphisms, isomorphisms, quotient groups, quotient rings, Sylow theorems, normal subgroups, cosets, Lagrange's theorem, polynomial rings, ideals, field extensions, Galois theory, group actions, and applications in cryptography and coding theory.
Calculus
119LTriggers when users need help with calculus concepts and problems. Activate for questions about limits, continuity, derivatives, integrals, series, Taylor expansions, Fourier series, vector calculus, gradient, divergence, curl, Stokes' theorem, Green's theorem, multivariable calculus, partial derivatives, chain rule, implicit differentiation, integration by parts, substitution, improper integrals, and applications of calculus in physics and engineering.
Complex Analysis
134LTriggers when users need help with complex analysis. Activate for questions about complex functions, analytic functions, holomorphic functions, Cauchy-Riemann equations, contour integration, Cauchy's integral theorem, Cauchy's integral formula, Laurent series, residue theorem, poles, singularities, conformal mappings, Mobius transformations, and applications in fluid dynamics and electrical engineering.
Differential Equations
122LTriggers when users need help with differential equations. Activate for questions about ODEs, PDEs, separable equations, exact equations, linear ODEs, Bernoulli equations, systems of ODEs, heat equation, wave equation, Laplace equation, Fourier series, Fourier transforms, Laplace transforms, numerical methods for ODEs, Euler method, Runge-Kutta, stability analysis, phase portraits, and boundary value problems.
Discrete Mathematics
128LTriggers when users need help with discrete mathematics. Activate for questions about combinatorics, permutations, combinations, pigeonhole principle, inclusion-exclusion, graph theory, paths, trees, graph coloring, planar graphs, network flow, recurrence relations, generating functions, Boolean algebra, lattices, partial orders, and applications of discrete math in computer science.
Geometry and Trigonometry
147LTriggers when users need help with geometry or trigonometry. Activate for questions about Euclidean geometry, coordinate geometry, geometric transformations, rotation, reflection, scaling, trigonometric functions, trigonometric identities, spherical geometry, projective geometry, differential geometry, curves, surfaces, curvature, geodesics, computational geometry algorithms, convex hulls, and Voronoi diagrams.
Linear Algebra
117LTriggers when users need help with linear algebra. Activate for questions about vectors, matrices, vector spaces, linear transformations, eigenvalues, eigenvectors, determinants, rank, null space, SVD, LU decomposition, QR decomposition, orthogonality, inner product spaces, least squares, matrix factorizations, and applications in machine learning, computer graphics, and physics.
Mathematical Logic
152LTriggers when users need help with mathematical logic and foundations. Activate for questions about propositional logic, predicate logic, proof techniques, direct proof, proof by contradiction, mathematical induction, contrapositive proofs, set theory, ZFC axioms, completeness theorem, incompleteness theorems, Godel, computability, decidability, model theory, formal verification, and automated theorem proving.
Mathematical Modeling
147LTriggers when users need help with mathematical modeling. Activate for questions about model formulation, dimensional analysis, scaling, population models, logistic growth, Lotka-Volterra predator-prey, diffusion models, network models, Monte Carlo simulation, sensitivity analysis, model validation, parameter estimation, compartmental models, epidemiological models, and communicating mathematical results.
Number Theory
125LTriggers when users need help with number theory. Activate for questions about divisibility, prime numbers, fundamental theorem of arithmetic, modular arithmetic, congruences, Euler's theorem, Fermat's little theorem, quadratic reciprocity, continued fractions, Diophantine equations, primality testing, RSA encryption, elliptic curve cryptography, the Chinese remainder theorem, and number-theoretic algorithms.
Numerical Methods
142LTriggers when users need help with numerical methods and scientific computing. Activate for questions about root finding, Newton's method, bisection method, secant method, interpolation, Lagrange interpolation, splines, numerical integration, Simpson's rule, Gaussian quadrature, numerical linear algebra, iterative solvers, condition numbers, numerical ODE solvers, numerical PDE solvers, floating-point arithmetic, error analysis, and numerical stability.
Optimization
129LTriggers when users need help with mathematical optimization. Activate for questions about linear programming, simplex method, interior point methods, convex optimization, gradient descent, Newton's method for optimization, proximal methods, constrained optimization, KKT conditions, Lagrange multipliers, integer programming, combinatorial optimization, metaheuristics, genetic algorithms, simulated annealing, and operations research.
Probability Theory
131LTriggers when users need help with probability theory and stochastic processes. Activate for questions about probability spaces, conditional probability, Bayes' theorem, random variables, probability distributions, normal distribution, Poisson distribution, exponential distribution, expectation, variance, moment generating functions, law of large numbers, central limit theorem, Markov chains, martingales, and stochastic modeling.
Real Analysis
119LTriggers when users need help with real analysis. Activate for questions about sequences, series of functions, metric spaces, compactness, connectedness, continuity, uniform continuity, pointwise and uniform convergence, differentiation theory, Riemann integration, Lebesgue integration, measure theory, sigma-algebras, function spaces, dominated convergence theorem, monotone convergence theorem, Fatou's lemma, and Lp spaces.
Topology
126LTriggers when users need help with topology. Activate for questions about topological spaces, open sets, closed sets, compactness, connectedness, Hausdorff spaces, continuous maps, homeomorphisms, homotopy, fundamental group, covering spaces, manifolds, point-set topology, algebraic topology, quotient topology, product topology, topological data analysis, and persistent homology.
Bayesian Statistics
116LTriggers when users need help with Bayesian inference, prior selection, posterior computation, or probabilistic modeling. Activate for questions about prior distributions, conjugate priors, Bayesian vs frequentist approaches, MCMC methods, Metropolis-Hastings, Gibbs sampling, Hamiltonian Monte Carlo, Bayesian model comparison, hierarchical models, Stan, PyMC, and probabilistic programming.
Causal Inference
143LTriggers when users need help establishing causal relationships from data, whether experimental or observational. Activate for questions about potential outcomes, Rubin causal model, DAGs, Pearl's framework, propensity scores, instrumental variables, difference-in-differences, regression discontinuity, synthetic control, mediation analysis, and sensitivity analysis for unmeasured confounding.
Descriptive Statistics
110LTriggers when users need help summarizing, describing, or exploring data distributions. Activate for questions about mean, median, mode, variance, standard deviation, IQR, skewness, kurtosis, five-number summary, box plots, histograms, outlier detection, data summarization, and exploratory data analysis techniques.
Experimental Design
125LTriggers when users need help designing experiments, clinical trials, or A/B tests. Activate for questions about randomized controlled trials, factorial designs, block designs, Latin square, split-plot designs, A/B testing methodology, power analysis, randomization, blinding, confounding, observational study design, and quasi-experimental methods.
Inferential Statistics
125LTriggers when users need help with hypothesis testing, confidence intervals, or drawing conclusions from sample data. Activate for questions about null and alternative hypotheses, p-values, Type I and II errors, statistical power, t-tests, ANOVA, chi-square tests, effect sizes, multiple comparisons, Bonferroni correction, FDR, and sample size determination.
Multivariate Statistics
137LTriggers when users need help analyzing datasets with multiple variables simultaneously. Activate for questions about PCA, principal component analysis, factor analysis, canonical correlation, MANOVA, discriminant analysis, cluster analysis, k-means, hierarchical clustering, DBSCAN, multidimensional scaling, correspondence analysis, and structural equation modeling.
Nonparametric Statistics
155LTriggers when users need help with distribution-free statistical methods or robust alternatives to parametric tests. Activate for questions about Mann-Whitney U, Wilcoxon signed-rank, Kruskal-Wallis, Spearman correlation, kernel density estimation, bootstrapping, permutation tests, rank-based methods, when to use nonparametric vs parametric tests, and robust statistics.
Regression Analysis
133LTriggers when users need help with regression modeling, prediction, or understanding relationships between variables. Activate for questions about linear regression, multiple regression, polynomial regression, logistic regression, generalized linear models, Ridge, Lasso, Elastic Net regularization, residual analysis, multicollinearity, heteroscedasticity, variable selection, and interaction effects.
Spatial Statistics
146LTriggers when users need help analyzing geographically referenced data or spatial patterns. Activate for questions about spatial autocorrelation, Moran's I, geostatistics, kriging, variograms, point process models, spatial regression, areal data analysis, GIS integration, spatial clustering, hot spot analysis, and applications in epidemiology, ecology, and urban planning.
Survey Sampling
146LTriggers when users need help designing surveys, selecting samples, or analyzing complex survey data. Activate for questions about simple random sampling, stratified sampling, cluster sampling, multistage sampling, systematic sampling, survey design, weighting, calibration, non-response adjustment, variance estimation for complex surveys, and questionnaire design principles.
Survival Analysis
151LTriggers when users need help analyzing time-to-event data, censored observations, or hazard modeling. Activate for questions about censoring, Kaplan-Meier estimator, log-rank test, Cox proportional hazards model, accelerated failure time models, competing risks, time-varying covariates, survival curves, reliability analysis, and customer churn modeling.
Time Series Analysis
136LTriggers when users need help with temporal data, forecasting, or time-dependent modeling. Activate for questions about stationarity, autocorrelation, ARIMA models, seasonal decomposition, exponential smoothing, GARCH, state space models, spectral analysis, change point detection, forecasting accuracy metrics, Prophet, and modern time series approaches.
Affine and Projective Varieties
183LActivate this skill when the user is working with the foundations of algebraic geometry: zero sets of polynomials, the Zariski topology, the dictionary between ideals and varieties, projective closures, dimension and singular points. Triggers on "affine variety," "projective variety," "Zariski topology," "Nullstellensatz," "homogenization," "projective closure," "irreducible components," "coordinate ring," "Jacobian criterion," "singular point," "twisted cubic," "smooth conic," or "algebraic geometry" foundations. Covers the ideal-variety correspondence, dimension theory, smoothness, and worked examples on the twisted cubic, conics and elliptic curves, each verified in Macaulay2, Singular or SageMath.
Algebraic Curves and Riemann-Roch
157LActivate this skill when the user is working with algebraic curves: genus, divisors, linear systems, the Riemann-Roch theorem and its consequences, elliptic curves and their group law, hyperelliptic curves, ramified covers and embeddings into projective space. Triggers on "algebraic curve," "Riemann-Roch," "genus," "divisor," "linear system," "canonical divisor," "canonical embedding," "hyperelliptic," "elliptic curve," "group law," "Weierstrass form," "Hurwitz formula," "Riemann-Hurwitz," "ramification," "degree-genus formula," "very ample," or curves in "algebraic geometry." Covers precise statements, worked Riemann-Roch computations for genus 0 through 3, the derivation of Weierstrass form and the group law, and how to check each computation in SageMath, Macaulay2 or Singular.
Algebraic Geometry Problem Solving
157LActivate this skill when the user has an algebraic geometry problem to attack rather than a definition to look up: a qualifying exam question, a lemma a paper needs, a conjecture to test, a proof a referee has questioned. Triggers on "how do I prove," "dimension count," "incidence correspondence," "general member," "generic," "Bertini," "semicontinuity," "local coordinates," "affine chart," "compute an example," "Gröbner check," "reduce mod p," "specialization," "degeneration," "standard tricks," "write the proof," "referee," "algebraic geometry exercise," or "algebraic geometry" problem solving. Covers the order of attack, dimension counting done rigorously, local coordinates and charts, choosing the right cohomological tool, what a computation proves and what it does not, how to write an argument that survives refereeing, and a catalogue of the tricks working geometers reach for first.
Commutative Algebra Toolkit
186LActivate this skill when the user needs the commutative algebra that algebraic geometry actually runs on, with every theorem tied to its geometric meaning. Triggers on "Noetherian ring," "localization," "local ring," "integral extension," "integral closure," "normalization," "Noether normalization," "Krull dimension," "primary decomposition," "associated primes," "embedded component," "regular local ring," "Cohen-Macaulay," "Hilbert polynomial," "Hilbert series," "depth," or requests to translate between ring theory and geometry. Covers the theorems, what each one says about a variety, and how to compute each invariant in Macaulay2, Singular and SageMath.
Gröbner Bases and Computation
179LActivate this skill when the user wants to compute with polynomial ideals: test membership, eliminate variables, solve polynomial systems, implicitize a parametrization, or understand why a computation will not finish. Triggers on "Gröbner basis," "Groebner basis," "monomial order," "lex order," "grevlex," "Buchberger algorithm," "S-polynomial," "division algorithm," "elimination ideal," "implicitization," "solving polynomial systems," "zero-dimensional ideal," "Macaulay2," "Singular," "SageMath," or computational "algebraic geometry." Covers the theory precisely, real sessions in Macaulay2, Singular and Sage with actual syntax, and the complexity facts that decide which computations are feasible.
Intersection Theory Basics
160LActivate this skill when the user needs to count intersections of subvarieties with the correct multiplicities, work with divisors and intersection numbers on surfaces, or reason about blow-ups and exceptional curves. Triggers on "Bézout's theorem," "Bezout," "intersection multiplicity," "intersection number," "Chow group," "Chow ring," "self-intersection," "(-1)-curve," "exceptional divisor," "blow-up," "adjunction formula," "Hodge index," "Riemann-Roch for surfaces," "27 lines," "cubic surface," or intersection-theoretic "algebraic geometry." Covers the local definition of multiplicity, Bézout in the plane and in P^n, the Chow ring of projective space and of products, the intersection pairing on surfaces with blow-ups and adjunction, and worked surface examples checked in Singular, Macaulay2 and Sage.
Schemes and Morphisms
153LActivate this skill when the user is learning or using the language of schemes: Spec and Proj, structure sheaves, generic points, nilpotents, fibre products, and the properties of morphisms that carry the geometry. Triggers on "scheme," "Spec," "Proj," "structure sheaf," "generic point," "nilpotent," "fibre product," "closed immersion," "open immersion," "separated," "proper morphism," "finite type," "finite morphism," "flat family," "flat limit," "valuative criterion," or "why schemes" in algebraic geometry. Covers the definitions with their reasons, the standard morphism properties and how to check them, flatness as continuity of fibres, and concrete computations of fibres and flat limits in Macaulay2 and Sage.
Sheaves and Cohomology
168LActivate this skill when the user needs to work with sheaves on varieties and schemes and to compute or use sheaf cohomology. Triggers on "sheaf," "quasi-coherent," "coherent sheaf," "line bundle," "invertible sheaf," "divisor," "Picard group," "Cech cohomology," "Čech cohomology," "sheaf cohomology," "H^1," "Serre duality," "canonical bundle," "vanishing theorem," "Kodaira vanishing," "Serre vanishing," "Castelnuovo-Mumford regularity," "long exact sequence," "ideal sheaf sequence," "Euler characteristic," "Hilbert polynomial," or cohomological "algebraic geometry." Covers the definitions, the divisor-line bundle dictionary, Čech computations done by hand on projective space, the statement and use of Serre duality, the vanishing theorems that actually get used, Euler characteristic bookkeeping, and how to check every number in Macaulay2, Singular or SageMath.
Toric Varieties
196LActivate this skill when the user is building or analysing toric varieties: turning cones, fans and lattice polytopes into varieties, reading smoothness, completeness and projectivity off the fan, computing torus-invariant divisors, their polytopes and sections, or resolving toric singularities by subdivision. Triggers on "toric variety," "fan," "rational polyhedral cone," "lattice polytope," "normal fan," "orbit-cone correspondence," "torus-invariant divisor," "Cox ring," "Hirzebruch surface," "weighted projective space," "Demazure vanishing," "Ehrhart polynomial," "Hilbert basis," "toric ideal," "reflexive polytope," "toric Fano," or combinatorial "algebraic geometry." Covers the cone-fan-polytope dictionary with precise statements, the criteria that decide geometry from combinatorics, divisors and cohomology through lattice points, and working sessions in SageMath, Macaulay2 and Singular.
Fourier Series and Convergence
160LActivate this skill when the user is expanding a periodic function in a Fourier series, computing coefficients for standard functions, or asking in what sense and how fast the series converges: pointwise, in L^2, uniformly, or through Cesàro and Abel summability. Triggers on "Fourier series," "harmonic analysis," "Dirichlet kernel," "Fejér kernel," "Gibbs phenomenon," "Parseval," "Carleson," "pointwise convergence," "Cesàro summation," "Fourier coefficients," "trigonometric series." Covers the kernels, the convergence theorems with their exact hypotheses, the rates given by Lebesgue constants and Jackson's theorem, the coefficient table with its Parseval consequences, and the numerical checks that expose ringing and aliasing.
Fourier Transform on R^n
155LActivate this skill when the user is defining, computing, or reasoning about the Fourier transform on R^n: picking a normalization, transforming Gaussians, derivatives, dilations or tempered distributions, or invoking Plancherel, inversion and the decay-smoothness duality inside a proof or a PDE argument. Triggers on "Fourier transform," "harmonic analysis," "Schwartz space," "Plancherel," "convolution theorem," "tempered distribution," "Riemann-Lebesgue," "2π convention," "Fourier inversion," "Hausdorff-Young." Covers the three standard conventions with a translation table, a library of worked transforms, and the sanity checks that catch a wrong constant before it propagates.