Test-function topology and distributions
Research context
postgraduate concept · established · As of 2026-10-10
A distribution on an open U in R-n is a continuous linear functional on smooth compactly supported test functions.
Key knowledge
A distribution on an open U in R-n is a continuous linear functional on smooth compactly supported test functions. Test-function convergence uses one fixed compact support and uniform convergence of every derivative. Locally integrable functions act by integration; the Dirac distribution acts by evaluation. Distributional convergence tests against each fixed test function and may preserve concentrated mass invisible to pointwise limits.
Values and equations
<delta_a,phi>=phi(a); <f,phi>=integral_U f(x)phi(x) dx
- delta_a
- Dirac distribution at a in U
- phi
- Smooth compactly supported test function
- f
- Locally integrable function
Conditions and scope
- U is open; continuity uses the test-function topology, not merely the supremum norm.
- Distributions can be multiplied by smooth functions; two arbitrary distributions have no generally defined product.
Sources · 1
References
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Evidence and review
Author checked this English statement, displayed equation where present and stated hypotheses against these source locations: §§1.2, 2.1–2.2, 3.1, 11.1–11.2, 12.1–12.2, 13.1, 15.1–15.3, 17.1–17.3; each record narrows its applicable claim. The check is bounded to the recorded claims; no complete proof reconstruction, software proof replay or universal literature completeness is claimed.
2026-10-10 · Author source-body/statement/equation/domain check, with graph associations scoped individually. Separate independent content/source/inventory review is required before branch closure.
Entry details
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- research-math-test-functions-distributions
- Revision
- research.1
- Structured reference record
- Postgraduate & research reference