Watch this clip to learn how we use the words atom, concept, and relation. Below is a list of other words with a specific meaning in Ampersand.
an indivisible item
to represent a thing
a name to categorize similar items
two atoms: a source and a target atom
to state that two atoms are related
a set of pairs that is identifyable in a context by its name and type
to build true statements and store pairs persistently in an application
a constraint, which is supposed to remain satisfied.
to provide meaning in a given context
A rule is satisfied (in a context) if the data (in that context) do not cause any violation of that rule.
to calculate violations at run-time helps users do the right things
a set of rules
to gather rules that belong together for reusing them in different contexts
a set of pairs in a context
POPULATION r[A*B] CONTAINS
[ ("Ida",5), ("Bob",1) ]
to represent the facts (i.e. true statements) in an information system
a population together with a set of rules that are satisfied by the population.
to maintain a consistent representation of a real life situation
A set of pairs that can be shown to users in a particular formulation.
to represent facts
A structure meant for "the outside world" to communicate with the system and possibly change the population.
INTERFACE Request FOR Customer
to let "the outside world" communicate with the system in a given context and possibly change its population
A predefined property of a relation
UNI, TOT, SUR, INJ
to constrain a relation with predefined properties
A combination of relations and operators that satisfy the Ampersand Syntax
to express rules
a symbol used in combining terms into other terms.
−, ⌣, ∪, ∩, ;, ∖, /, ⊆, =
to express more complex rules.
A name for a group of people
ROLE Customer MAINTAINS paymentObligation
to talk about users without having any users