CVP verified calculation capability

Subtraction Calculation Capability

Difference a − b with solve-for any missing term, plus optional long subtraction.

Math Capability ID math.subtraction version 1.0.1 CVP VERIFIED CURRENT Core

Model

Difference

Difference: Minuend − Subtrahend = Difference
As addition: a − b = a + (−b)
Inverse: If a + b = c then c − a = b and c − b = a

Modes: difference · long

Inputs / Outputs

Canonical symbols for this capability. Agent schemas remain the contract.

Symbol	Quantity	Unit	Role
`minuend`	—	—	input / output
`subtrahend`	—	—	input / output
`difference`	—	—	input / output
`minInput`	Share-URL alias for minuend	—	input
`subInput`	Share-URL alias for subtrahend	—	input
`diffInput`	Share-URL alias for difference	—	input
`value`	—	—	output

Trusted Math contract

Inspectable numeric contract for this Capability@Version. Not a rewrite of the engine.

Field	Declaration
`numeric_domain`	real
`exactness`	float64
`algorithm`	float64 a − b
`valid_domain`	finite reals a, b
`singularity_policy`	not applicable — subtraction has no pole
`branch_policy`	not applicable — real principal value only
`tolerance`	not applicable — closed form; capability Evidence owns comparison, no global default
`convergence`	not applicable — non-iterative
`conditioning`	not applicable — not a matrix κ product
`rounding`	ieee754_round_ties_to_even
`overflow`	ieee754_nonfinite_or_coded_error
`reproducibility`	deterministic algorithm + Capability@Version
`independent_oracle`	cvp:math.subtraction / Evidence published cases
`golden_vectors`	Evidence golden + boundary + property (and published_reference_case when listed)

Assumptions / Validity

Declared scope for this capability. Do not use it outside this domain.

Assumptions

Difference mode: finite reals; scientific notation allowed.
Long subtraction: non-negative decimal numbers without scientific notation.
Order is minuend − subtrahend. When minuend < subtrahend the difference is negative; long mode still stacks the minuend on top. Column work subtracts the smaller magnitude from the larger, then applies the sign.

Example

One numerical check. The calculator page holds worked steps and FAQ.

245 − 147 = 98

Open this example in the calculator

Trust

CVP VERIFIED · CVP protocol 1.0.0-proposed · Core assurance. Computational verification is defined by CVP. Supplemental domain review (internal) and named expert review are defined by the Review policy and do not by themselves determine CVP conformance.

CVP: CVP VERIFIED · CVP protocol 1.0.0-proposed · Core assurance· View Manifest · CVP overview · Specification
Assurance: Core
Declared partition coverage: PASS · 6/6 declared partitions (difference, solve-for-minuend, solve-for-subtrahend, long-normal, long-negative-result, invalid-domain)
Calculation version: 1.0.1
Verification: 7/7 calculation tests · 6/6 legacy golden · 1/1 legacy boundary
Production surface contract: 3/3
Versions: Calculation 1.0.1 · CVP protocol 1.0.0-proposed · Evidence 2026-09-16.sources-no-wolfram
Verification revision: 2026-09-16.sources-no-wolfram · 2/2 property · digest c11ae651671e
Reference: O1 model · O2 expected_values · O2 numerical_behavior
Numerical scope: ≤2 ULP on the numeric value for difference, solve-for-minuend, solve-for-subtrahend, and long-mode difference. Column-work strings and regrouping steps are not an O2 numerical claim.
Interfaces: PASS · UI (SSR) / REST / MCP
ui-ssr is query-result HTML, not a live browser session. Error-path engine·REST·MCP 1/1 (status, code, calculation_version). SSR compared on URL-canonical requested calculations; empty query is idle (not an error) and JSON-typed object/array inputs are REST/MCP-only.
CVP suite: 5/5 golden · 1/1 CVP boundary · 3/3 invalid · 2/2 property · 1/1 metamorphic · 2/2 round-trip · 5/5 cross-interface · 1/1 CVP contract
Supplemental domain review: Not performed
Named expert review: Not performed
Version lock: Supported (409 VERSION_MISMATCH)
Artifact consistency: Build verified · 1.0.1 (workspace artifacts agree)
Review-policy tier: Engine tested — catalog token engine_tested; supplemental; not CVP status

This calculator CURRENT · Public schema 1.0.1 matches · Semantic contract ✓ · Production attested · Public/cache ✓ · Origin ✓

Call this capability

Human page, REST, and MCP share the same engine and calculation_version. Build verified hashes workspace artifacts only. After deploy, attest:production GETs canonical URLs twice — the public/cached view an Agent actually hits, and origin — including every /capabilities/{id} HTML page. Public Capability HTML version must match catalog before production attestation passes. Live Trust rows above fetch /.well-known/calculatorx-production-attestation.json and the output schema const. Build hashes: release integrity. That proves currently published page / engine / schema / evidence / MCP agree — not that a historical version is independently immutable. Reference Calculation Standard — Production surface contract 3/3.

curl -sS -X POST 'https://www.calculatorx.com/api/v1/calc/subtraction' \
  -H 'Content-Type: application/json' \
  -d '{"inputs":{"mode":"difference","a":8,"b":3},"calculation_version":"1.0.1"}'

{
  "inputs": {
    "mode": "difference",
    "a": 8,
    "b": 3
  },
  "calculation_version": "1.0.1"
}

POST /api/v1/calc/subtraction. This is a POST calculate endpoint — do not GET it.

Full REST contract: REST API docs.

Tool id: subtraction
Engine: subtraction
REST: POST /api/v1/calc/subtraction
MCP: execute_calculation with capability_id: "math.subtraction"
Agent input schema: Canonical (MCP / Agent)
Output schema: JSON Schema (latest)
Versioned input schema: Immutable pin (1.0.1)
Versioned output schema: Immutable pin (1.0.1)

References

Human-readable sources plus CVP reference evidence classes.

Sources

Margaret Stevens — The Maths Workbook (University of Oxford) — Chapter 1, §1: Algebraic Expressions and Fractions; §3: Equations

Derived identities

CalculatorX mathematical conventions — Long subtraction with regrouping

Reference evidence classes: O1 model · O2 expected_values · O2 numerical_behavior

Try with an agent

Inspect, then execute. Same engine as REST and the human calculator.

curl -sS -X POST 'https://www.calculatorx.com/mcp' \
  -H 'Content-Type: application/json' \
  -H 'MCP-Protocol-Version: 2026-07-28' \
  -H 'Mcp-Method: tools/call' \
  -H 'Mcp-Name: inspect_capability' \
  -d '{"jsonrpc":"2.0","id":1,"method":"tools/call","params":{"name":"inspect_capability","arguments":{"capability_id":"math.subtraction"},"_meta":{"io.modelcontextprotocol/protocolVersion":"2026-07-28","io.modelcontextprotocol/clientInfo":{"name":"calculatorx-docs-example","version":"1.0.0"},"io.modelcontextprotocol/clientCapabilities":{}}}}'

curl -sS -X POST 'https://www.calculatorx.com/mcp' \
  -H 'Content-Type: application/json' \
  -H 'MCP-Protocol-Version: 2026-07-28' \
  -H 'Mcp-Method: tools/call' \
  -H 'Mcp-Name: execute_calculation' \
  -d '{"jsonrpc":"2.0","id":2,"method":"tools/call","params":{"name":"execute_calculation","arguments":{"capability_id":"math.subtraction","inputs":{"mode":"difference","a":8,"b":3},"calculation_version":"1.0.1"},"_meta":{"io.modelcontextprotocol/protocolVersion":"2026-07-28","io.modelcontextprotocol/clientInfo":{"name":"calculatorx-docs-example","version":"1.0.0"},"io.modelcontextprotocol/clientCapabilities":{}}}}'

Pin calculation_version (1.0.1) when the result must stay reproducible.

Inspect the trust tier and required assurance level before execution. Full protocol notes: MCP docs.