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Parseval's identity
Parseval's identity, also known as Rayleigh's energy theorem, is a Fourier analysis result equating a signal's energy in the time domain with the energy of its frequency components.
Parshall flume
The Parshall flume is an open-channel flow-measuring structure invented by Ralph Parshall in 1922, which converts upstream water depth into discharge and is widely used for irrigation and wastewater.
Parsing expression grammar
A parsing expression grammar (PEG) is a formalism for describing syntax in which rules are recognition procedures with ordered choice, formalized by Bryan Ford in 2004.
Parsley force field
Parsley is the codename for the Open Force Field Initiative's first generation of small molecule force fields, released as OpenFF 1.0.0 in October 2019 and succeeded by Sage.
Part III of the Mathematical Tripos
Part III of the Mathematical Tripos, also called the Certificate of Advanced Studies in Mathematics, is a nine-month taught master's course in mathematics at the University of Cambridge.
Partha Sarathi Mukherjee
Partha Sarathi Mukherjee, born 1973, is an Indian supramolecular coordination chemist at the Indian Institute of Science, Bangalore, known for Pd(II) and Pt(II) molecular cages and barrels used in catalysis.
Partial charge
A partial charge is a non-integer atomic charge assigned to an atom in a molecule to represent uneven electron distribution, with no unique correct value.
Partial correlation
Partial correlation, written r12.3, is the correlation between two variables after control variables' linear influence is removed from both, as if the controls were held constant.
Partial derivative
A partial derivative, or partial differentiation, is the derivative of a multivariable function with respect to one variable, the others held constant, computed with ordinary differentiation rules.
Partial differential equation
A partial differential equation (PDE) is an equation for a function of several variables involving its partial derivatives, describing how quantities vary in space and time.
Partial differential sign
∂, called the partial differential sign or "curly d", is the mathematical symbol for partial derivatives, which differentiate one variable while the others are held constant.
Partial fraction decomposition
Partial fraction decomposition, or partial fraction expansion, rewrites a rational function as a polynomial plus simpler fractions, the standard first step for integrating rational functions.
Partial function
A partial function from X to Y assigns at most one value to each element of X but need not be defined everywhere; total functions are the special case.
Partial information decomposition
Partial information decomposition is an information theory framework that splits what multiple sources reveal about a target into redundant, unique, and synergistic components, introduced by Williams and Beer in 2010.
Partial least squares discriminant analysis
Partial least squares discriminant analysis (PLS-DA) is a supervised classification method that runs PLS regression against dummy-coded class labels, widely used in metabolomics and spectroscopy but prone to overfitting.
Partial least squares path modeling
Partial least squares path modeling (PLS-SEM, also called PLS-PM) is a variance-based structural equation modeling method estimating latent variables as weighted composites, suited to small samples.
Partial least squares regression
Partial least squares regression (PLS) projects many correlated predictors onto a few latent components and regresses on them; proposed by Herman Wold in the 1960s.
Partial melting
Partial melting, also called anatexis, is the transformation of part of a solid rock into liquid magma, caused by decompression, heat input, or added water rather than complete melting.
Partial order reduction
Partial order reduction is a model checking technique that combats state explosion in concurrent systems by exploiting independence between transitions, preserving properties like LTL without the next operator.
Partial pressure
Partial pressure is the pressure a gas in a mixture would exert if it alone occupied the whole volume at the same temperature, summed per Dalton's law.
Partial volume effect
The partial volume effect (PVE) is an imaging artifact in which a voxel contains more than one material, so its recorded value is an average of their properties.
Partial wave analysis
Partial wave analysis (PWA) is a scattering-theory method that decomposes reaction amplitudes into angular momentum components, extracting phase shifts, inelasticities, and resonance masses and widths from data.
Partial word
A partial word is a finite or infinite sequence over a finite alphabet in which some positions, called holes, are undefined; it extends ordinary words in combinatorics on words.
Partially observable Markov decision process
A partially observable Markov decision process (POMDP) is a mathematical model for sequential decision-making under uncertainty, where an agent acts on noisy observations and a belief state.
Partially ordered set
A partially ordered set, or poset, is a set with a reflexive, antisymmetric, transitive relation, so some elements rank relative to each other while others are unrelated.
Partially stabilized zirconia
Partially stabilized zirconia is a zirconium dioxide ceramic whose metastable tetragonal phase gives transformation toughening, high strength, and high fracture toughness for industrial and dental uses.
Participatory action research
Participatory action research (PAR) is a collaborative social-science method in which researchers and community members jointly investigate problems and act on findings, aiming for social change.
Participatory evaluation
Participatory evaluation is an approach to evaluating programs and policies in which stakeholders such as staff, participants, and community members share control over the process.
Participatory GIS
Participatory GIS (PGIS) is a social-science research method in which community members collaboratively create and analyze GIS maps, so local spatial knowledge enters planning, research, and advocacy.
Participatory learning and action
Participatory learning and action (PLA) is a family of qualitative research approaches in which community members, rather than outside experts, analyze their own situation and act on it.