<reduction> In beta reduction, when a term containing a free occurrence of a variable v is substituted into another term where v is bound the free v becomes spuriously bound or "captured". E.g. ( x . y . x y) y --> y . y y (WRONG) This problem arises because two distinct variables have the same name. The most common solution is to rename the bound variable using alpha conversion: ( x . y' . x y') y --> y' . y y' Another solution is to use de Bruijn notation. Note that the argument expression, y, contained a {free variable}. The whole expression above must therefore be notionally contained within the body of some {lambda abstraction} which binds y. If we never reduce inside the body of a lambda abstraction (as in reduction to {weak head normal form}) then name capture cannot occur. (1995-03-14)

Electron capture (K-electron capture, also K-capture, or L-electron capture, L-capture) is a process in which the proton-rich nucleus of an electrically neutral atom absorbs an inner atomic electron, usually from the K or L electron shells. This process thereby changes a nuclear proton to a neutron and simultaneously causes the emission of an electron neutrino.

Carbon capture and storage (CCS) or carbon capture and sequestration is the process of capturing carbon dioxide (CO2) before it enters the atmosphere, transporting it, and storing it (carbon sequestration) for centuries or millennia. Usually the CO2 is captured from large point sources, such as a chemical plant or biomass power plant, and then stored in an underground geological formation.