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twoand

Twoand is a term used in theoretical discussions of logic and reactive programming to denote a dual-input conjunction operator with a temporal synchronization constraint. In this sense, twoand extends the ordinary boolean AND by requiring that both inputs not only be true, but also be observed within a defined time window. The operator is described here as a conceptual tool for illustrating how conjunction can be conditioned on arrival timing in streaming settings.

Formal definition: Let a and b be boolean streams with associated timestamps. A twoand operation with window

Applications and implementations: Twoand is used in discussions of sensor fusion, event correlation, and real-time monitoring

Relation to other concepts and limitations: It is closely related to temporal logic, the standard AND operation,

W
yields
an
output
event
when
there
exists
a
pair
of
input
events
(a_i,
b_j)
such
that
a_i
is
true,
b_j
is
true,
and
|t_i
−
t_j|
≤
W.
The
result
can
be
modeled
as
a
boolean
signal
that
is
true
only
for
such
synchronized
pairs;
in
other
cases,
the
output
may
be
false
or
omitted
depending
on
the
implementation.
Variants
may
use
different
delay
strategies
or
produce
multi-valued
outputs
to
reflect
synchronization
status.
where
both
conditions
must
be
affirmed
in
close
temporal
proximity.
In
software,
it
can
be
implemented
as
an
operator
in
streaming
libraries,
similar
to
zip,
combineLatest,
or
temporal
and
gate
operators,
but
with
a
windowed
temporal
constraint.
and
to
windowed
combinators
in
reactive
programming.
It
introduces
complexity
in
semantics
and
may
reduce
throughput
due
to
waiting
for
synchronization.
As
a
hypothetical
construct,
twoand
is
not
an
established
standard.