FA-96786 / Phone number formatting / Open access

Numbering prefix pattern classifier: digits inside a class count as literals · case 01

"7[0-4]" outranks the more specific literal "72".

Verified by executionVariant 1 · 9 checks per implementationDownload source bundle ↓JSON ↗

ROOT CAUSE

The score counts digit characters inside brackets as literal digits.

VERIFIED REPAIR

Score digits only outside brackets; a whole class scores 1.

Unsuccessful approach: Ignoring classes in the score ties "7[0-4]" with "7X" and the wildcard wins by order.

Case contract

Input [number, rules] with rules [pattern, label] in priority order. Pattern characters: X any digit, [..] a class of single digits and inclusive ranges a-b, other characters literal. A pattern matches when each of its positions matches the corresponding number digit (the number may be longer). Score: literal digit 2, class 1, X 0; the highest score wins and ties keep the earlier rule. No match gives "unknown".

Why this case matters

Numbering-plan tables decide routing, rating and number type from prefixes; specificity and range errors misroute whole blocks of numbers.

1 / The failure

Exit 1

"""Failure Map reference implementation. Python standard library only."""
import json

N = 1
observations = []
def solve(x):
    num, rules = x
    def match(p, s):
        i = k = 0
        while k < len(p):
            if i >= len(s):
                return False
            if p[k] == 'X':
                ok = s[i].isdigit()
                k += 1
            elif p[k] == '[':
                end = p.index(']', k)
                body, ok, j = p[k + 1:end], False, 0
                while j < len(body):
                    if j + 2 < len(body) and body[j + 1] == '-':
                        ok = ok or body[j] <= s[i] <= body[j + 2]
                        j += 3
                    else:
                        ok = ok or s[i] == body[j]
                        j += 1
                k = end + 1
            else:
                ok = s[i] == p[k]
                k += 1
            if not ok:
                return False
            i += 1
        return True
    def score(p):
        total, depth = 0, 0
        for c in p:
            if c == '[':
                depth += 1
            elif c == ']':
                depth -= 1
                total += 1
            elif c.isdigit():
                total += 2
        return total
    best = None
    for p, label in rules:
        if match(p, num):
            sc = score(p)
            if best is None or sc > best[0]:
                best = (sc, label)
    return best[1] if best else 'unknown'
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[['class beats wildcard', ['72555012', [['7X', 'generic'], ['7[0-4]', 'mobile']]], 'mobile'], ['literal beats class', ['72555012', [['7[0-4]', 'mobile'], ['72', 'special']]], 'special'], ['range upper end inclusive', ['74555012', [['7[0-4]', 'mobile'], ['7X', 'generic']]], 'mobile'], ['range lower end inclusive', ['70555012', [['7[0-4]', 'mobile'], ['7X', 'generic']]], 'mobile'], ['number shorter than the pattern', ['7', [['7X', 'generic']]], 'unknown'], ['tie keeps the first listed rule', ['88555012', [['X8', 'listed-first'], ['8X', 'listed-second']]], 'listed-first'], ['range then literal in one class', ['2555012', [['[0-35]X', 'class-range']]], 'class-range'], ['literal then range in one class', ['5555012', [['[50-3]X', 'class-literal']]], 'class-literal'], ['no rule matches', ['6555012', [['7X', 'generic']]], 'unknown']], [['class beats wildcard', ['72555023', [['7X', 'generic'], ['7[0-4]', 'mobile']]], 'mobile'], ['literal beats class', ['72555023', [['7[0-4]', 'mobile'], ['72', 'special']]], 'special'], ['range upper end inclusive', ['74555023', [['7[0-4]', 'mobile'], ['7X', 'generic']]], 'mobile'], ['range lower end inclusive', ['70555023', [['7[0-4]', 'mobile'], ['7X', 'generic']]], 'mobile'], ['number shorter than the pattern', ['7', [['7X', 'generic']]], 'unknown'], ['tie keeps the first listed rule', ['88555023', [['X8', 'listed-first'], ['8X', 'listed-second']]], 'listed-first'], ['range then literal in one class', ['2555023', [['[0-35]X', 'class-range']]], 'class-range'], ['literal then range in one class', ['5555023', [['[50-3]X', 'class-literal']]], 'class-literal'], ['no rule matches', ['6555023', [['7X', 'generic']]], 'unknown']], [['class beats wildcard', ['72555034', [['7X', 'generic'], ['7[0-4]', 'mobile']]], 'mobile'], ['literal beats class', ['72555034', [['7[0-4]', 'mobile'], ['72', 'special']]], 'special'], ['range upper end inclusive', ['74555034', [['7[0-4]', 'mobile'], ['7X', 'generic']]], 'mobile'], ['range lower end inclusive', ['70555034', [['7[0-4]', 'mobile'], ['7X', 'generic']]], 'mobile'], ['number shorter than the pattern', ['7', [['7X', 'generic']]], 'unknown'], ['tie keeps the first listed rule', ['88555034', [['X8', 'listed-first'], ['8X', 'listed-second']]], 'listed-first'], ['range then literal in one class', ['2555034', [['[0-35]X', 'class-range']]], 'class-range'], ['literal then range in one class', ['5555034', [['[50-3]X', 'class-literal']]], 'class-literal'], ['no rule matches', ['6555034', [['7X', 'generic']]], 'unknown']], [['class beats wildcard', ['72555045', [['7X', 'generic'], ['7[0-4]', 'mobile']]], 'mobile'], ['literal beats class', ['72555045', [['7[0-4]', 'mobile'], ['72', 'special']]], 'special'], ['range upper end inclusive', ['74555045', [['7[0-4]', 'mobile'], ['7X', 'generic']]], 'mobile'], ['range lower end inclusive', ['70555045', [['7[0-4]', 'mobile'], ['7X', 'generic']]], 'mobile'], ['number shorter than the pattern', ['7', [['7X', 'generic']]], 'unknown'], ['tie keeps the first listed rule', ['88555045', [['X8', 'listed-first'], ['8X', 'listed-second']]], 'listed-first'], ['range then literal in one class', ['2555045', [['[0-35]X', 'class-range']]], 'class-range'], ['literal then range in one class', ['5555045', [['[50-3]X', 'class-literal']]], 'class-literal'], ['no rule matches', ['6555045', [['7X', 'generic']]], 'unknown']], [['class beats wildcard', ['72555056', [['7X', 'generic'], ['7[0-4]', 'mobile']]], 'mobile'], ['literal beats class', ['72555056', [['7[0-4]', 'mobile'], ['72', 'special']]], 'special'], ['range upper end inclusive', ['74555056', [['7[0-4]', 'mobile'], ['7X', 'generic']]], 'mobile'], ['range lower end inclusive', ['70555056', [['7[0-4]', 'mobile'], ['7X', 'generic']]], 'mobile'], ['number shorter than the pattern', ['7', [['7X', 'generic']]], 'unknown'], ['tie keeps the first listed rule', ['88555056', [['X8', 'listed-first'], ['8X', 'listed-second']]], 'listed-first'], ['range then literal in one class', ['2555056', [['[0-35]X', 'class-range']]], 'class-range'], ['literal then range in one class', ['5555056', [['[50-3]X', 'class-literal']]], 'class-literal'], ['no rule matches', ['6555056', [['7X', 'generic']]], 'unknown']]]
for label, arg, expected in fixtures[N - 1]:
    check(label, solve(arg), expected)
print(json.dumps({"observations": observations, "passed": all(x["passed"] for x in observations)}, ensure_ascii=False))
raise SystemExit(0 if all(x["passed"] for x in observations) else 1)

Boundary fixture	Actual	Expected	Outcome
class beats wildcard	`mobile`	`mobile`	Passed
literal beats class	`mobile`	`special`	Failed
range upper end inclusive	`mobile`	`mobile`	Passed
range lower end inclusive	`mobile`	`mobile`	Passed
number shorter than the pattern	`unknown`	`unknown`	Passed
tie keeps the first listed rule	`listed-first`	`listed-first`	Passed
range then literal in one class	`class-range`	`class-range`	Passed
literal then range in one class	`class-literal`	`class-literal`	Passed
no rule matches	`unknown`	`unknown`	Passed

SHA-256 / 673d5c7fa15c47631f855573935ca378bd9dd637110b15000c819960e7af58e5

2 / The unsuccessful fix

Exit 1

"""Failure Map reference implementation. Python standard library only."""
import json

N = 1
observations = []
def solve(x):
    num, rules = x
    def match(p, s):
        i = k = 0
        while k < len(p):
            if i >= len(s):
                return False
            if p[k] == 'X':
                ok = s[i].isdigit()
                k += 1
            elif p[k] == '[':
                end = p.index(']', k)
                body, ok, j = p[k + 1:end], False, 0
                while j < len(body):
                    if j + 2 < len(body) and body[j + 1] == '-':
                        ok = ok or body[j] <= s[i] <= body[j + 2]
                        j += 3
                    else:
                        ok = ok or s[i] == body[j]
                        j += 1
                k = end + 1
            else:
                ok = s[i] == p[k]
                k += 1
            if not ok:
                return False
            i += 1
        return True
    def score(p):
        total, depth = 0, 0
        for c in p:
            if c == '[':
                depth += 1
            elif c == ']':
                depth -= 1
            elif c.isdigit() and depth == 0:
                total += 2
        return total
    best = None
    for p, label in rules:
        if match(p, num):
            sc = score(p)
            if best is None or sc > best[0]:
                best = (sc, label)
    return best[1] if best else 'unknown'
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[['class beats wildcard', ['72555012', [['7X', 'generic'], ['7[0-4]', 'mobile']]], 'mobile'], ['literal beats class', ['72555012', [['7[0-4]', 'mobile'], ['72', 'special']]], 'special'], ['range upper end inclusive', ['74555012', [['7[0-4]', 'mobile'], ['7X', 'generic']]], 'mobile'], ['range lower end inclusive', ['70555012', [['7[0-4]', 'mobile'], ['7X', 'generic']]], 'mobile'], ['number shorter than the pattern', ['7', [['7X', 'generic']]], 'unknown'], ['tie keeps the first listed rule', ['88555012', [['X8', 'listed-first'], ['8X', 'listed-second']]], 'listed-first'], ['range then literal in one class', ['2555012', [['[0-35]X', 'class-range']]], 'class-range'], ['literal then range in one class', ['5555012', [['[50-3]X', 'class-literal']]], 'class-literal'], ['no rule matches', ['6555012', [['7X', 'generic']]], 'unknown']], [['class beats wildcard', ['72555023', [['7X', 'generic'], ['7[0-4]', 'mobile']]], 'mobile'], ['literal beats class', ['72555023', [['7[0-4]', 'mobile'], ['72', 'special']]], 'special'], ['range upper end inclusive', ['74555023', [['7[0-4]', 'mobile'], ['7X', 'generic']]], 'mobile'], ['range lower end inclusive', ['70555023', [['7[0-4]', 'mobile'], ['7X', 'generic']]], 'mobile'], ['number shorter than the pattern', ['7', [['7X', 'generic']]], 'unknown'], ['tie keeps the first listed rule', ['88555023', [['X8', 'listed-first'], ['8X', 'listed-second']]], 'listed-first'], ['range then literal in one class', ['2555023', [['[0-35]X', 'class-range']]], 'class-range'], ['literal then range in one class', ['5555023', [['[50-3]X', 'class-literal']]], 'class-literal'], ['no rule matches', ['6555023', [['7X', 'generic']]], 'unknown']], [['class beats wildcard', ['72555034', [['7X', 'generic'], ['7[0-4]', 'mobile']]], 'mobile'], ['literal beats class', ['72555034', [['7[0-4]', 'mobile'], ['72', 'special']]], 'special'], ['range upper end inclusive', ['74555034', [['7[0-4]', 'mobile'], ['7X', 'generic']]], 'mobile'], ['range lower end inclusive', ['70555034', [['7[0-4]', 'mobile'], ['7X', 'generic']]], 'mobile'], ['number shorter than the pattern', ['7', [['7X', 'generic']]], 'unknown'], ['tie keeps the first listed rule', ['88555034', [['X8', 'listed-first'], ['8X', 'listed-second']]], 'listed-first'], ['range then literal in one class', ['2555034', [['[0-35]X', 'class-range']]], 'class-range'], ['literal then range in one class', ['5555034', [['[50-3]X', 'class-literal']]], 'class-literal'], ['no rule matches', ['6555034', [['7X', 'generic']]], 'unknown']], [['class beats wildcard', ['72555045', [['7X', 'generic'], ['7[0-4]', 'mobile']]], 'mobile'], ['literal beats class', ['72555045', [['7[0-4]', 'mobile'], ['72', 'special']]], 'special'], ['range upper end inclusive', ['74555045', [['7[0-4]', 'mobile'], ['7X', 'generic']]], 'mobile'], ['range lower end inclusive', ['70555045', [['7[0-4]', 'mobile'], ['7X', 'generic']]], 'mobile'], ['number shorter than the pattern', ['7', [['7X', 'generic']]], 'unknown'], ['tie keeps the first listed rule', ['88555045', [['X8', 'listed-first'], ['8X', 'listed-second']]], 'listed-first'], ['range then literal in one class', ['2555045', [['[0-35]X', 'class-range']]], 'class-range'], ['literal then range in one class', ['5555045', [['[50-3]X', 'class-literal']]], 'class-literal'], ['no rule matches', ['6555045', [['7X', 'generic']]], 'unknown']], [['class beats wildcard', ['72555056', [['7X', 'generic'], ['7[0-4]', 'mobile']]], 'mobile'], ['literal beats class', ['72555056', [['7[0-4]', 'mobile'], ['72', 'special']]], 'special'], ['range upper end inclusive', ['74555056', [['7[0-4]', 'mobile'], ['7X', 'generic']]], 'mobile'], ['range lower end inclusive', ['70555056', [['7[0-4]', 'mobile'], ['7X', 'generic']]], 'mobile'], ['number shorter than the pattern', ['7', [['7X', 'generic']]], 'unknown'], ['tie keeps the first listed rule', ['88555056', [['X8', 'listed-first'], ['8X', 'listed-second']]], 'listed-first'], ['range then literal in one class', ['2555056', [['[0-35]X', 'class-range']]], 'class-range'], ['literal then range in one class', ['5555056', [['[50-3]X', 'class-literal']]], 'class-literal'], ['no rule matches', ['6555056', [['7X', 'generic']]], 'unknown']]]
for label, arg, expected in fixtures[N - 1]:
    check(label, solve(arg), expected)
print(json.dumps({"observations": observations, "passed": all(x["passed"] for x in observations)}, ensure_ascii=False))
raise SystemExit(0 if all(x["passed"] for x in observations) else 1)

Boundary fixture	Actual	Expected	Outcome
class beats wildcard	`generic`	`mobile`	Failed
literal beats class	`special`	`special`	Passed
range upper end inclusive	`mobile`	`mobile`	Passed
range lower end inclusive	`mobile`	`mobile`	Passed
number shorter than the pattern	`unknown`	`unknown`	Passed
tie keeps the first listed rule	`listed-first`	`listed-first`	Passed
range then literal in one class	`class-range`	`class-range`	Passed
literal then range in one class	`class-literal`	`class-literal`	Passed
no rule matches	`unknown`	`unknown`	Passed

SHA-256 / d8f00527eada26d15514277fd45d6bad45cfb2ec2ae0c155bf66052fd5d1156e

3 / The verified repair

Exit 0

"""Failure Map reference implementation. Python standard library only."""
import json

N = 1
observations = []
def solve(x):
    num, rules = x
    def match(p, s):
        i = k = 0
        while k < len(p):
            if i >= len(s):
                return False
            if p[k] == 'X':
                ok = s[i].isdigit()
                k += 1
            elif p[k] == '[':
                end = p.index(']', k)
                body, ok, j = p[k + 1:end], False, 0
                while j < len(body):
                    if j + 2 < len(body) and body[j + 1] == '-':
                        ok = ok or body[j] <= s[i] <= body[j + 2]
                        j += 3
                    else:
                        ok = ok or s[i] == body[j]
                        j += 1
                k = end + 1
            else:
                ok = s[i] == p[k]
                k += 1
            if not ok:
                return False
            i += 1
        return True
    def score(p):
        total, depth = 0, 0
        for c in p:
            if c == '[':
                depth += 1
            elif c == ']':
                depth -= 1
                total += 1
            elif c.isdigit() and depth == 0:
                total += 2
        return total
    best = None
    for p, label in rules:
        if match(p, num):
            sc = score(p)
            if best is None or sc > best[0]:
                best = (sc, label)
    return best[1] if best else 'unknown'
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[['class beats wildcard', ['72555012', [['7X', 'generic'], ['7[0-4]', 'mobile']]], 'mobile'], ['literal beats class', ['72555012', [['7[0-4]', 'mobile'], ['72', 'special']]], 'special'], ['range upper end inclusive', ['74555012', [['7[0-4]', 'mobile'], ['7X', 'generic']]], 'mobile'], ['range lower end inclusive', ['70555012', [['7[0-4]', 'mobile'], ['7X', 'generic']]], 'mobile'], ['number shorter than the pattern', ['7', [['7X', 'generic']]], 'unknown'], ['tie keeps the first listed rule', ['88555012', [['X8', 'listed-first'], ['8X', 'listed-second']]], 'listed-first'], ['range then literal in one class', ['2555012', [['[0-35]X', 'class-range']]], 'class-range'], ['literal then range in one class', ['5555012', [['[50-3]X', 'class-literal']]], 'class-literal'], ['no rule matches', ['6555012', [['7X', 'generic']]], 'unknown']], [['class beats wildcard', ['72555023', [['7X', 'generic'], ['7[0-4]', 'mobile']]], 'mobile'], ['literal beats class', ['72555023', [['7[0-4]', 'mobile'], ['72', 'special']]], 'special'], ['range upper end inclusive', ['74555023', [['7[0-4]', 'mobile'], ['7X', 'generic']]], 'mobile'], ['range lower end inclusive', ['70555023', [['7[0-4]', 'mobile'], ['7X', 'generic']]], 'mobile'], ['number shorter than the pattern', ['7', [['7X', 'generic']]], 'unknown'], ['tie keeps the first listed rule', ['88555023', [['X8', 'listed-first'], ['8X', 'listed-second']]], 'listed-first'], ['range then literal in one class', ['2555023', [['[0-35]X', 'class-range']]], 'class-range'], ['literal then range in one class', ['5555023', [['[50-3]X', 'class-literal']]], 'class-literal'], ['no rule matches', ['6555023', [['7X', 'generic']]], 'unknown']], [['class beats wildcard', ['72555034', [['7X', 'generic'], ['7[0-4]', 'mobile']]], 'mobile'], ['literal beats class', ['72555034', [['7[0-4]', 'mobile'], ['72', 'special']]], 'special'], ['range upper end inclusive', ['74555034', [['7[0-4]', 'mobile'], ['7X', 'generic']]], 'mobile'], ['range lower end inclusive', ['70555034', [['7[0-4]', 'mobile'], ['7X', 'generic']]], 'mobile'], ['number shorter than the pattern', ['7', [['7X', 'generic']]], 'unknown'], ['tie keeps the first listed rule', ['88555034', [['X8', 'listed-first'], ['8X', 'listed-second']]], 'listed-first'], ['range then literal in one class', ['2555034', [['[0-35]X', 'class-range']]], 'class-range'], ['literal then range in one class', ['5555034', [['[50-3]X', 'class-literal']]], 'class-literal'], ['no rule matches', ['6555034', [['7X', 'generic']]], 'unknown']], [['class beats wildcard', ['72555045', [['7X', 'generic'], ['7[0-4]', 'mobile']]], 'mobile'], ['literal beats class', ['72555045', [['7[0-4]', 'mobile'], ['72', 'special']]], 'special'], ['range upper end inclusive', ['74555045', [['7[0-4]', 'mobile'], ['7X', 'generic']]], 'mobile'], ['range lower end inclusive', ['70555045', [['7[0-4]', 'mobile'], ['7X', 'generic']]], 'mobile'], ['number shorter than the pattern', ['7', [['7X', 'generic']]], 'unknown'], ['tie keeps the first listed rule', ['88555045', [['X8', 'listed-first'], ['8X', 'listed-second']]], 'listed-first'], ['range then literal in one class', ['2555045', [['[0-35]X', 'class-range']]], 'class-range'], ['literal then range in one class', ['5555045', [['[50-3]X', 'class-literal']]], 'class-literal'], ['no rule matches', ['6555045', [['7X', 'generic']]], 'unknown']], [['class beats wildcard', ['72555056', [['7X', 'generic'], ['7[0-4]', 'mobile']]], 'mobile'], ['literal beats class', ['72555056', [['7[0-4]', 'mobile'], ['72', 'special']]], 'special'], ['range upper end inclusive', ['74555056', [['7[0-4]', 'mobile'], ['7X', 'generic']]], 'mobile'], ['range lower end inclusive', ['70555056', [['7[0-4]', 'mobile'], ['7X', 'generic']]], 'mobile'], ['number shorter than the pattern', ['7', [['7X', 'generic']]], 'unknown'], ['tie keeps the first listed rule', ['88555056', [['X8', 'listed-first'], ['8X', 'listed-second']]], 'listed-first'], ['range then literal in one class', ['2555056', [['[0-35]X', 'class-range']]], 'class-range'], ['literal then range in one class', ['5555056', [['[50-3]X', 'class-literal']]], 'class-literal'], ['no rule matches', ['6555056', [['7X', 'generic']]], 'unknown']]]
for label, arg, expected in fixtures[N - 1]:
    check(label, solve(arg), expected)
print(json.dumps({"observations": observations, "passed": all(x["passed"] for x in observations)}, ensure_ascii=False))
raise SystemExit(0 if all(x["passed"] for x in observations) else 1)

Boundary fixture	Actual	Expected	Outcome
class beats wildcard	`mobile`	`mobile`	Passed
literal beats class	`special`	`special`	Passed
range upper end inclusive	`mobile`	`mobile`	Passed
range lower end inclusive	`mobile`	`mobile`	Passed
number shorter than the pattern	`unknown`	`unknown`	Passed
tie keeps the first listed rule	`listed-first`	`listed-first`	Passed
range then literal in one class	`class-range`	`class-range`	Passed
literal then range in one class	`class-literal`	`class-literal`	Passed
no rule matches	`unknown`	`unknown`	Passed

SHA-256 / 1f76afe85952c4a5a0ee9ba5a5aff4620aa9559d96b258b26daa31e775cc3366

Verification & scope

A deterministic toy contract over synthetic, obviously fictitious telephone numbers and toy country tables. The rules are stipulated for this model only and make no claim of conformance with any numbering plan or telecommunications standard. This reproducer isolates one failure mechanism. Results cover the supplied fixtures. Variants within a family share a test contract and should remain grouped when constructing evaluation splits. Related mechanisms with a shared evaluation_group must also remain together; these controlled models are not independent production incidents.

Observations recorded using Python 3.12.14 at 2026-09-29T14:52:25.865241+00:00.

Case digest / df13165c1c4a3513ecb72ce0a54939851ab406fe9da7b83a1ee1791aaecf6bb7