561 Group Market

FOUR Evidence Negation

Swap told-for and told-against sides of one FOUR point. Held becomes denied; unknown and contested remain fixed. Preserve the input name family. Refuse unknown names before payment; this transforms a point, not testimony or its authority.

Price
$0.001 USDC per request
Network
Base mainnet, eip155:8453, settled in USDC through the Coinbase CDP facilitator
Method and URL
POST https://market.561.group/v1/four/reading-negate
Response type
application/json
Seller
Causeway Services (561 Group)

Input contract

Input that fails this contract is refused with a 4xx status before any payment is requested.

{
  "maxBytes": 102400,
  "bodySchema": {
    "type": "object",
    "additionalProperties": true,
    "required": [
      "name"
    ],
    "properties": {
      "name": {
        "type": "string",
        "enum": [
          "absurd",
          "potential",
          "active",
          "stable",
          "told none",
          "told true",
          "told false",
          "told both",
          "neither",
          "true",
          "false",
          "both",
          "unknown",
          "held",
          "denied",
          "contested"
        ]
      }
    }
  }
}

Example request

{
  "method": "POST",
  "url": "https://market.561.group/v1/four/reading-negate",
  "headers": {
    "accept": "application/json",
    "content-type": "application/json"
  },
  "body": {
    "name": "held"
  }
}

Output

{
  "schema": {
    "type": "string",
    "enum": [
      "absurd",
      "potential",
      "active",
      "stable",
      "told none",
      "told true",
      "told false",
      "told both",
      "neither",
      "true",
      "false",
      "both",
      "unknown",
      "held",
      "denied",
      "contested"
    ]
  },
  "example": "denied"
}

How to buy with x402

  1. Send the request without payment. The server answers 402 Payment Required with a base64 JSON PAYMENT-REQUIRED header holding the amount, asset, network and payee.
  2. Have your wallet sign an EIP-3009 transferWithAuthorization for exactly those terms (an x402 client library does this for you).
  3. Repeat the identical request with the signed payload in the PAYMENT-SIGNATURE header.
  4. The server verifies, runs the operation, settles, and returns 200 with the result and a PAYMENT-RESPONSE header carrying the settlement receipt.

Read the price without paying

curl --include --request POST --header 'accept: application/json' --header 'content-type: application/json' --data-raw '{"name":"held"}' --url 'https://market.561.group/v1/four/reading-negate'

This request authorizes nothing; it returns the live payment terms. Read the full explanation of x402.

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