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ReLU6 Output Preimage Interval Tool

Represent the complete ReLU6 preimage with explicit unbounded flags and finite placeholder endpoints.

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Description

Return lower=upper=output with unbounded flags at zero/six; interior outputs have singleton=true.

ReLU clips negative input to zero; ReLU6 also clips above six. Saturated outputs have entire input rays as preimages, unlike interior values with single inverses. At a ReLU kink a selected subgradient is not an ordinary two-sided derivative.

Return lower=upper=output with unbounded flags at zero/six; interior outputs have singleton=true.

When to use this tool

Use ReLU6 Output Preimage Interval when checking the stated rectifier value, inverse region or subgradient convention.

How to use the tool and how it works

  1. Enter output. Use the units and conventions below.
  2. Run the tool. Correct any format, range, or cross-field input error before interpreting the output.
  3. Read lower, upper, lowerUnbounded, upperUnbounded, singleton. Inspect lowerUnbounded, upperUnbounded, singleton before interpreting the associated values.

Require output in [0,6]. Return lower=upper=output with unbounded flags at zero/six; interior outputs have singleton=true.1

Input fieldMeaning and unitsAccepted input
outputOutputRequired. Finite number; minimum 0; maximum 6.
Output fieldInterpretationReturned shape
lowerFinite output boundary marker; lowerUnbounded=true replaces it by -∞ as an interval end.Required. Finite number.
upperFinite output boundary marker; upperUnbounded=true replaces it by +∞ as an interval end.Required. Finite number.
lowerUnboundedLower UnboundedRequired. Boolean.
upperUnboundedUpper UnboundedRequired. Boolean.
singletonSingletonRequired. Boolean.
json
{
  "input": {
    "output": 0
  },
  "output": {
    "lower": 0,
    "upper": 0,
    "lowerUnbounded": true,
    "upperUnbounded": false,
    "singleton": false
  }
}

Limitations and assumptions

  • At zero the preimage is (-∞,0], and at six it is [6,∞). Numeric endpoints are finite boundary markers, not a full singleton when an unbounded flag is true.
  • Inputs must satisfy both the field types and the cross-field conditions above. Invalid input causes an error; a successful false flag or documented placeholder is a different result.
  • Numeric calculations use binary floating point unless exact decimal-integer arithmetic is explicitly stated. No hidden measurement tolerance or decimal rounding is added; nonfinite or out-of-contract results are rejected. Numeric signed-zero results are exported as zero.

Alternative or Complementary methods

Use the complete explicit function and the intended parameter, branch and numerical conventions for symbolic, tensor or model-level differentiation; assess training behavior independently.

References

  1. Calculation and input contract: activation/relu6-output-preimage-interval — tool.io

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