(logic) Any of a set of rules used to construct well-formed formulas of a formal language.

plural of formation rule

(logic) A well-formed formula which has not been made by combining simpler well-formed formulas by means of logical connectives.

A new formation (a subsequent coming together of the elements of a former grouping)

(chemistry) A structural formula which is reduced (i.e., skeletal) in the sense that carbon atoms forming the backbone of the structure (esp. of an organic compound) are not labeled — they are shown simply as vertices — and hydrogen atoms are not shown at all (except those which are bonded to heteroatoms, or the exceptionally labeled carbon atoms) but heteroatoms are always labeled. (Labels of labeled hydrogen atoms are written next to labels of the atoms that they are bonded to, without a bond drawn between them. If there are several labeled hydrogen atoms bonded to the same atom then they are written as an H with a subscript for their number.) Carbon atoms which are (optionally) labeled tend to be in reactive extremities of the molecule, not the backbone of it.

(organic chemistry) A skeletal formula, especially a schematic representation of benzene as a hexagon made up of alternating single and double lines that represent alternating single and double bonds

(computing, artificial intelligence) A computer language designed for communicating knowledge between independently running computer programs.

(UK, Australia) A pupil in the sixth form.

(biology) The mechanism in developing tissue by which originally similar cells acquire diverse forms and functions by coordinated cell fate control.

(logic) An argument's property of being valid due to being an instance of an argument form.