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statementsI

StatementsI is a notational convention used in logic and philosophy to denote the collection of statements that are indexed by a set I. Formally, it refers to an indexed family {s_i} of statements, where each s_i belongs to a fixed language and i ranges over the index set I. The term emphasizes that the truth of each member can depend on the index i, and that discussions often concern properties that hold uniformly across all indices or for particular subfamilies.

The notation is a shorthand in formal discussions; it does not introduce a new kind of primitive

In model theory and related fields, indexed families of formulas are central to arguments about compactness,

See also: indexed family, index set, first-order logic, model theory, parametric proofs, families of formulas.

object
beyond
the
individual
statements,
but
it
clarifies
when
a
discussion
concerns
an
entire
family
rather
than
a
single
proposition.
In
practice,
statementsI
may
be
used
to
express
universal
or
existential
quantifications
over
indices,
to
formulate
parametric
proofs,
or
to
study
how
logical
properties
vary
with
the
index
parameter.
completeness,
and
transfer
principles.
The
framework
for
statementsI
supports
reasoning
about
families,
counterexamples,
and
limit
processes
by
treating
the
index
set
as
a
parameter
space.