21-letter words containing w, o, n, d, e
- weak head normal form — (reduction, theory) (WHNF) A lambda expression is in weak head normal form (WHNF) if it is a head normal form (HNF) or any lambda abstraction. I.e. the top level is not a redex. The term was coined by Simon Peyton Jones to make explicit the difference between head normal form (HNF) and what graph reduction systems produce in practice. A lambda abstraction with a reducible body, e.g. \ x . ((\ y . y+x) 2) is in WHNF but not HNF. To reduce this expression to HNF would require reduction of the lambda body: (\ y . y+x) 2 --> 2+x Reduction to WHNF avoids the name capture problem with its need for alpha conversion of an inner lambda abstraction and so is preferred in practical graph reduction systems. The same principle is often used in strict languages such as Scheme to provide call-by-name evaluation by wrapping an expression in a lambda abstraction with no arguments: D = delay E = \ () . E The value of the expression is obtained by applying it to the empty argument list:
- well-ordering theorem — the theorem of set theory that every set can be made a well-ordered set.
- wet collodion process — a photographic process, in common use in the mid-19th century, employing a glass photographic plate coated with iodized collodion and dipped in a silver nitrate solution immediately before use.
- whip-and-tongue graft — a graft prepared by cutting both the scion and the stock in a sloping direction and inserting a tongue in the scion into a slit in the stock.
- white-crowned sparrow — a North American sparrow, Zonotrichia leucophrys, having black and white stripes on the head.
- wholesale price index — an indicator of price changes in the wholesale market
- with one's bare hands — If someone does something with their bare hands, they do it without using any weapons or tools.
- word association test — a technique for determining a subject's associative pattern by providing a verbal stimulus to which a verbal response is required.
- word-association test — a psychological test in which the person being tested responds to a given word with the first word (or the first word in a specified category, such as an antonym) brought to mind