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  2. Restriction (mathematics) - Wikipedia

    en.wikipedia.org/wiki/Restriction_(mathematics)

    More generally, the restriction (or domain restriction or left-restriction) of a binary relation between and may be defined as a relation having domain , codomain and graph ( ) = {(,) ():}. Similarly, one can define a right-restriction or range restriction R B . {\displaystyle R\triangleright B.}

  3. List of unsolved problems in chemistry - Wikipedia

    en.wikipedia.org/wiki/List_of_unsolved_problems...

    Protein folding problem: Is it possible to predict the secondary, tertiary and quaternary structure of a polypeptide sequence based solely on the sequence and environmental information? Inverse protein-folding problem: Is it possible to design a polypeptide sequence which will adopt a given structure under certain environmental conditions?

  4. Crystallographic restriction theorem - Wikipedia

    en.wikipedia.org/wiki/Crystallographic...

    The crystallographic restriction theorem in its basic form was based on the observation that the rotational symmetries of a crystal are usually limited to 2-fold, 3-fold, 4-fold, and 6-fold. However, quasicrystals can occur with other diffraction pattern symmetries, such as 5-fold; these were not discovered until 1982 by Dan Shechtman .

  5. Restricted representation - Wikipedia

    en.wikipedia.org/wiki/Restricted_representation

    Restriction to a normal subgroup behaves particularly well and is often called Clifford theory after the theorem of A. H. Clifford. [1] Restriction can be generalized to other group homomorphisms and to other rings. For any group G, its subgroup H, and a linear representation ρ of G, the restriction of ρ to H, denoted

  6. Corestriction - Wikipedia

    en.wikipedia.org/wiki/Corestriction

    In mathematics, a corestriction [1] of a function is a notion analogous to the notion of a restriction of a function. The duality prefix co- here denotes that while the restriction changes the domain to a subset, the corestriction changes the codomain to a subset. However, the notions are not categorically dual.

  7. Gibbs–Duhem equation - Wikipedia

    en.wikipedia.org/wiki/Gibbs–Duhem_equation

    Gibbs derived the relationship based on the though experiment of varying the amount of substance starting from zero, keeping its nature and state the same. [ 3 ] Mathematically, this means the internal energy U {\displaystyle U} scales with its extensive variables as follows: [ 6 ] U ( λ S , λ V , λ N 1 , λ N 2 , …

  8. Reaction–diffusion system - Wikipedia

    en.wikipedia.org/wiki/Reaction–diffusion_system

    Reaction–diffusion systems are naturally applied in chemistry. However, the system can also describe dynamical processes of non-chemical nature. Examples are found in biology, geology and physics (neutron diffusion theory) and ecology. Mathematically, reaction–diffusion systems take the form of semi-linear parabolic partial differential ...

  9. Energy minimization - Wikipedia

    en.wikipedia.org/wiki/Energy_minimization

    In the field of computational chemistry, energy minimization (also called energy optimization, geometry minimization, or geometry optimization) is the process of finding an arrangement in space of a collection of atoms where, according to some computational model of chemical bonding, the net inter-atomic force on each atom is acceptably close to zero and the position on the potential energy ...