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Regla del año bisiesto: (div4 AND NOT div100) OR div400

La regla gregoriana del año bisiesto, (div4 AND NOT div100) OR div400, con los hechos aritméticos div400 -> div100 y div100 -> div4 declarados como supuestos. Cuatro de las ocho filas son imposibles, y el mapa de Karnaugh las trata como indiferencias.

Un año es bisiesto si es divisible por 4 pero no por 100, o si es divisible por 400. Las tres entradas son indicadores de divisibilidad, y dos no varían libremente: todo lo divisible por 400 lo es por 100, y todo lo divisible por 100 lo es por 4. El modelo lo declara como supuestos k1 y k2. En la tabla la salida es verdadera en cinco filas, Σm(1, 3, 4, 5, 7), pero las columnas de los supuestos son falsas en las filas 1, 2, 3 y 5, y quedan cuatro años posibles, las filas 0, 4, 6 y 7, como 2023, 2024, 1900 y 2000.

Las comprobaciones se ejecutan sobre la función completa: no es tautología, contraejemplo los tres indicadores en FALSO; satisfacible, testigo div4 = VERDADERO, div100 = FALSO, div400 = FALSO. El simplificador no encontró ninguna ley que acorte la regla de tres operadores, y la FND es la original. La FNC, tras una distributividad, es (div4 OR div400) AND (NOT div100 OR div400). El mapa marca 4 indiferencias de los dos supuestos, dibuja div4 AND NOT div100 y div400, informa de tres implicantes primos y deriva la regla original, etiquetada como equivalente dentro de los supuestos. Compuertas: 4 NAND, NAND(NAND(div4, NAND(div100, div100)), NAND(div400, div400)), y 7 NOR.

Esta regla está en todas las bibliotecas de fechas y se reimplementa mal con cierta regularidad, normalmente omitiendo el caso del 400. La página muestra una segunda sutileza: las entradas no son independientes, y un generador de pruebas que enumere las ocho combinaciones de indicadores producirá años imposibles. Lo que hay que vigilar es que las indiferencias del motor vienen solo de los supuestos declarados; el resultado derivado con ellas se afirma solo para los años que los satisfacen, que, para la divisibilidad, son todos, pero el modelo no puede saberlo.

leap := (div4 AND NOT div100) OR div400 · salida

Supuestos: div400 -> div100 (A year divisible by 400 is divisible by 100.); div100 -> div4 (A year divisible by 100 is divisible by 4.)

Comprobaciones exactas

¿Siempre verdadera (tautología)? No Contraejemplo: div4 = F, div100 = F, div400 = F · Exhaustively checked and solver cross-checked · 1 filas
¿Siempre falsa (contradicción)? No Contraejemplo: div4 = V, div100 = F, div400 = F · Exhaustively checked and solver cross-checked · 5 filas
¿Puede ser verdadera? Sí Asignación de ejemplo: div4 = V, div100 = F, div400 = F · Exhaustively checked and solver cross-checked · 5 filas
¿Son consistentes los supuestos? Sí Asignación de ejemplo: div4 = F, div100 = F, div400 = F · Exhaustively checked and solver cross-checked · 1 filas

Tabla de verdad (8 filas)

Regla del año bisiesto: (div4 AND NOT div100) OR div400
#div4div100div400leapk1k2Ámbito
0FALSOFALSOFALSOFALSOVERDADEROVERDADEROen ámbito
1FALSOFALSOVERDADEROVERDADEROFALSOVERDADEROexcluida
2FALSOVERDADEROFALSOFALSOVERDADEROFALSOexcluida
3FALSOVERDADEROVERDADEROVERDADEROVERDADEROFALSOexcluida
4VERDADEROFALSOFALSOVERDADEROVERDADEROVERDADEROen ámbito
5VERDADEROFALSOVERDADEROVERDADEROFALSOVERDADEROexcluida
6VERDADEROVERDADEROFALSOFALSOVERDADEROVERDADEROen ámbito
7VERDADEROVERDADEROVERDADEROVERDADEROVERDADEROVERDADEROen ámbito

Lectura en lenguaje claro

Principianteleap es verdadero exactamente cuando se cumple al menos una de las condiciones siguientes (pueden cumplirse ambas):
1. div4 es verdadero y div100 es falso
2. div400 es verdadero
En todos los demás casos, leap es falso.
Sobre los operadores:
- OR (O) es inclusivo: es verdadero en cuanto al menos una parte es verdadera, también cuando lo son varias.
- AND (Y) solo es verdadero cuando todas sus partes son verdaderas.
- NOT (NO) invierte un valor: lo verdadero pasa a ser falso y lo falso, verdadero.
Intermedioleap es verdadero exactamente cuando se cumple al menos una de las condiciones siguientes (pueden cumplirse ambas):
1. div4 es verdadero y div100 es falso
2. div400 es verdadero
En todos los demás casos, leap es falso.
Avanzadoleap es verdadero exactamente cuando se cumple al menos una de las condiciones siguientes (pueden cumplirse ambas) [disyunción inclusiva ∨]:
1. div4 es verdadero y div100 es falso [conjunción ∧]
2. div400 es verdadero
En todos los demás casos, leap es falso.
Notación formal: (div4 ∧ ¬div100) ∨ div400

Diagrama lógico

Leap year rule: (div4 AND NOT div100) OR div400 Leap year rule: (div4 AND NOT div100) OR div400 div4 div100 div400 leap k1ASSUME k2ASSUME OR AND NOT → →
Leap year rule: (div4 AND NOT div100) OR div400 Leap year rule: (div4 AND NOT div100) OR div400 div4 div100 div400 leap k1ASSUME k2ASSUME OR AND NOT → →

Simplificación paso a paso

El motor no encontró ninguna ley que acorte esta expresión; ya es tan corta como sus leyes de reescritura permiten.

(div4 AND NOT div100) OR div400

Mapa de Karnaugh

div4 \ div100div400
00
01
11
10
0
0m0
Xm1
Xm3
Xm2
1
1m4
Xm5
1m7
0m6
  1. celdas m4, m5div4 AND NOT div100
  2. celdas m1, m3, m5, m7div400
(div4 AND NOT div100) OR div400 · Derived (div4 AND NOT div100) OR div400. The groups use don't-care cells, so the result is only claimed within the assumptions. Equivalent on every assignment the assumptions allow (scoped: it was derived using the assumptions); no claim is made outside them.

4 cells excluded by the confirmed assumptions (k1, k2) are marked don't-care. An expression derived with them is equivalent only within the assumptions.

Mintérminos y maxtérminos

leap(div4, div100, div400) = Σm(1, 3, 4, 5, 7)leap(div4, div100, div400) = ΠM(0, 2, 6)

Orden de variables: div4, div100, div400 · 8 filas

Formas normales

Forma normal conjuntiva (FNC)

(div4 OR div400) AND (NOT div100 OR div400)

2 cláusulas, 4 literales · complete · Distributividad ×1

Forma normal disyuntiva (FND)

(div4 AND NOT div100) OR div400

2 términos, 3 literales · complete

Solo NAND, solo NOR

Forma solo con NAND

NAND(NAND(div4, NAND(div100, div100)), NAND(div400, div400))

4 compuertas · equivalencia verificada en todas las filas

Forma solo con NOR

NOR(NOR(NOR(NOR(div4, div4), div100), div400), NOR(NOR(NOR(div4, div4), div100), div400))

7 compuertas · equivalencia verificada en todas las filas

La misma regla como código

Python
# -*- coding: utf-8 -*-
# Generated by Tangibool (tangibool.python/1). Do not edit by hand; regenerate from the source revision.
# Model: not stated
# Source revision: reference
# Interpretation status: not stated
"""Tangibool evaluator (decision model).

Generated deterministically from the validated Boolean model; it evaluates exactly that
model. It does not establish that the model is a complete, legal, or safe statement of a
real-world rule, and evaluating examples does not verify the rule.

Source revision: reference
Interpretation status: not stated
Exporter: 1.0.0 (format tangibool.python/1; engine 1.0.0; semantics tangibool-semantics/1)
Logic digest: 5469380ed02d1805f827fb98e06c6d3f30c3e855fe470b8e6e9fb099b023d732
Assumptions digest: c95d45363e428617061214db272f6ed6c809bda4bf8b9545d8c63b031323bc7c

Inputs (dict keys, declared order) and generated parameter names:
    'div4' -> input_div4
    'div100' -> input_div100
    'div400' -> input_div400

Outputs (declared order) and their functions:
    'leap' -> output_leap(inputs)

Assumptions (the declared scope, checked by in_scope(inputs)):
    'k1': div400 -> div100
    'k2': div100 -> div4

Input contract:
    Every required input must be exactly True or False (type(value) is bool). Missing
    inputs, None, strings, integers (including 0 and 1), and keys that are not declared
    inputs raise InputError before anything is evaluated, including inputs that a
    short-circuiting operator would never read. Results are always bool.

Scope:
    Decision functions raise OutOfScopeError when the inputs violate an assumption; an
    out-of-scope assignment is never turned into a False result. Pass check_scope=False
    to evaluate without the scope check, and use in_scope(inputs) to test it separately.

Usage:

    import tangibool_model as model

    model.evaluate({'div4': False, 'div100': False, 'div400': False})
    # -> {'leap': False}
    model.output_leap({'div4': False, 'div100': False, 'div400': False})
    # -> False
    model.evaluate({'div4': 1, 'div100': False, 'div400': False})
    # raises InputError: 1 is an int, not a bool
"""

import collections.abc as _abc
from typing import Dict, Mapping, Tuple

__all__ = [
    "MODEL_INFO",
    "IDENTIFIER_MAP",
    "INPUT_NAMES",
    "OUTPUT_NAMES",
    "ASSUMPTIONS",
    "InputError",
    "OutOfScopeError",
    "minterm_index",
    "in_scope",
    "evaluate",
    "output_leap",
    "assumption_k1",
    "assumption_k2",
]

MODEL_INFO = {
    "format": "tangibool.python/1",
    "mode": "decision",
    "model": None,
    "revision": "reference",
    "interpretation": None,
    "exporter": "1.0.0",
    "engine_version": "1.0.0",
    "semantics_version": "tangibool-semantics/1",
    "logic_digest": "5469380ed02d1805f827fb98e06c6d3f30c3e855fe470b8e6e9fb099b023d732",
    "assumptions_digest": "c95d45363e428617061214db272f6ed6c809bda4bf8b9545d8c63b031323bc7c",
    "primary_output": "leap",
    "unused_inputs": (),
    "subcircuits": (),
}

# Stable ID -> generated identifier (reversible mapping; names are exact, escaped strings).
IDENTIFIER_MAP = {
    "v_3b217ba27c75": {"kind": "input", "name": "div4", "identifier": "input_div4"},
    "v_e132c27d17cf": {"kind": "input", "name": "div100", "identifier": "input_div100"},
    "v_2440ffcf4122": {"kind": "input", "name": "div400", "identifier": "input_div400"},
    "f_46b25eaf9240": {"kind": "output", "name": "leap", "identifier": "output_leap"},
    "f_bdb57448a020": {"kind": "assumption", "name": "k1", "identifier": "assumption_k1"},
    "f_c8cf788fb953": {"kind": "assumption", "name": "k2", "identifier": "assumption_k2"},
}

INPUT_NAMES = ("div4", "div100", "div400")
OUTPUT_NAMES = ("leap",)
ASSUMPTIONS = (
    {"name": "k1", "id": "f_bdb57448a020", "formula": "div400 -> div100", "description": "A year divisible by 400 is divisible by 100."},
    {"name": "k2", "id": "f_c8cf788fb953", "formula": "div100 -> div4", "description": "A year divisible by 100 is divisible by 4."},
)

_DECLARED_INPUTS = frozenset(INPUT_NAMES)
_SCOPE_INPUTS = ("div4", "div100", "div400")
_ASSUMPTION_FORMULAS = {entry["name"]: entry["formula"] for entry in ASSUMPTIONS}


class InputError(ValueError):
    """Raised when inputs are missing, undeclared, or not exactly True/False.

    Every required input must satisfy type(value) is bool. Missing inputs, None, strings,
    integers (including 0 and 1), and keys that are not declared inputs are rejected before
    anything is evaluated. A missing input is never treated as False. The individual problems
    are listed in the problems attribute.
    """

    def __init__(self, problems):
        self.problems = tuple(problems)
        super().__init__("Invalid inputs: " + "; ".join(self.problems))


class OutOfScopeError(ValueError):
    """Raised when the inputs violate the model's assumptions (its declared scope).

    Outside its assumptions the rule has no decision: this error is never a False result.
    The names of the violated assumptions are in the violated attribute.
    """

    def __init__(self, violated):
        self.violated = tuple(violated)
        details = ", ".join(name + " (" + _ASSUMPTION_FORMULAS.get(name, "?") + ")" for name in self.violated)
        super().__init__(
            "Out of scope: the inputs violate "
            + ("assumption " if len(self.violated) == 1 else "assumptions ")
            + details
            + ". The rule has no decision outside its assumptions; this is not a False result."
        )


def _short_repr(value: object) -> str:
    text = repr(value)
    return text if len(text) <= 60 else text[:57] + "..."


def _checked_inputs(inputs: Mapping[str, bool], required: Tuple[str, ...], check_scope: bool) -> Dict[str, bool]:
    """Validate inputs strictly before anything is evaluated and return a plain copy."""
    if type(check_scope) is not bool:
        raise TypeError("check_scope must be True or False")
    if not isinstance(inputs, _abc.Mapping):
        raise InputError(["inputs must be a mapping from input names to True/False, got " + type(inputs).__name__])
    problems = []
    for key in inputs:
        if type(key) is not str or key not in _DECLARED_INPUTS:
            declared = ", ".join(repr(name) for name in INPUT_NAMES) or "none"
            problems.append("undeclared input " + _short_repr(key) + " (declared inputs: " + declared + ")")
    needed = tuple(required) + (_SCOPE_INPUTS if check_scope else ())
    for name in needed:
        if name not in inputs:
            problems.append("missing required input " + repr(name))
    for key, value in inputs.items():
        if type(key) is str and key in _DECLARED_INPUTS and type(value) is not bool:
            problems.append(
                "input " + repr(key) + " must be True or False (type bool), got "
                + type(value).__name__ + " " + _short_repr(value)
            )
    if problems:
        raise InputError(list(dict.fromkeys(problems)))
    return dict(inputs.items())


def _require_bool_args(function: str, pairs: Tuple[Tuple[str, object], ...]) -> None:
    problems = [
        "argument " + repr(name) + " of " + function + " must be True or False (type bool), got "
        + type(value).__name__ + " " + _short_repr(value)
        for name, value in pairs
        if type(value) is not bool
    ]
    if problems:
        raise InputError(problems)


def minterm_index(*values: bool) -> int:
    """Row index of an assignment over a declared variable order.

    The first value is the most significant bit, so all-False is row 0. Used for indexed
    minterm (sum) and maxterm (product) forms.
    """
    index = 0
    for value in values:
        if type(value) is not bool:
            raise InputError(["minterm_index() takes True/False values, got " + type(value).__name__ + " " + _short_repr(value)])
        index = index * 2 + (1 if value else 0)
    return index


def _scope_values(values: Dict[str, bool]) -> Tuple[Tuple[str, bool], ...]:
    """Value of every enabled, confirmed assumption for validated inputs, in declared order."""
    assumption_k1_value = _compute_assumption_k1(values["div100"], values["div400"])
    assumption_k2_value = _compute_assumption_k2(values["div4"], values["div100"])
    return (
        ("k1", assumption_k1_value),
        ("k2", assumption_k2_value),
    )


def _require_in_scope(values: Dict[str, bool]) -> None:
    violated = tuple(name for name, holds in _scope_values(values) if not holds)
    if violated:
        raise OutOfScopeError(violated)


def in_scope(inputs: Mapping[str, bool]) -> bool:
    """True when the inputs satisfy every assumption (the model's declared scope).

    Requires the inputs the assumptions read; raises InputError for invalid inputs.
    """
    values = _checked_inputs(inputs, (), True)
    return all(holds for _, holds in _scope_values(values))


# ---- Formula bodies (inputs are validated by the public functions below) ----


def _compute_output_leap(input_div4: bool, input_div100: bool, input_div400: bool) -> bool:
    """Decision output 'leap': (div4 AND NOT div100) OR div400"""
    return (input_div4 and (not input_div100)) or input_div400


def _compute_assumption_k1(input_div100: bool, input_div400: bool) -> bool:
    """Assumption 'k1': div400 -> div100"""
    return (not input_div400) or input_div100


def _compute_assumption_k2(input_div4: bool, input_div100: bool) -> bool:
    """Assumption 'k2': div100 -> div4"""
    return (not input_div100) or input_div4


# ---- Public API ----


def output_leap(inputs: Mapping[str, bool], *, check_scope: bool = True) -> bool:
    """Decision output 'leap' (stable ID f_46b25eaf9240).

    'leap' := (div4 AND NOT div100) OR div400

    Required inputs: 'div4', 'div100', 'div400'; with check_scope=True also 'div4', 'div100', 'div400' (read by the assumptions).
    Raises InputError for missing, undeclared, or non-bool inputs, and OutOfScopeError
    when check_scope is True and the inputs violate an assumption.
    """
    values = _checked_inputs(inputs, ("div4", "div100", "div400"), check_scope)
    if check_scope:
        _require_in_scope(values)
    output_leap_value = _compute_output_leap(values["div4"], values["div100"], values["div400"])
    return output_leap_value


def evaluate(inputs: Mapping[str, bool], *, check_scope: bool = True) -> Dict[str, bool]:
    """Evaluate every output (declared order); each output is computed once.

    Required inputs: 'div4', 'div100', 'div400'; with check_scope=True also 'div4', 'div100', 'div400' (read by the assumptions).
    Raises InputError for missing, undeclared, or non-bool inputs, and OutOfScopeError
    when check_scope is True and the inputs violate an assumption.
    """
    values = _checked_inputs(inputs, ("div4", "div100", "div400"), check_scope)
    if check_scope:
        _require_in_scope(values)
    output_leap_value = _compute_output_leap(values["div4"], values["div100"], values["div400"])
    return {
        "leap": output_leap_value,
    }


def assumption_k1(inputs: Mapping[str, bool]) -> bool:
    """Assumption 'k1' (stable ID f_bdb57448a020).

    'k1' := div400 -> div100

    Description: A year divisible by 400 is divisible by 100.

    Required inputs: 'div100', 'div400'.
    Raises InputError for missing, undeclared, or non-bool inputs.
    """
    values = _checked_inputs(inputs, ("div100", "div400"), False)
    assumption_k1_value = _compute_assumption_k1(values["div100"], values["div400"])
    return assumption_k1_value


def assumption_k2(inputs: Mapping[str, bool]) -> bool:
    """Assumption 'k2' (stable ID f_c8cf788fb953).

    'k2' := div100 -> div4

    Description: A year divisible by 100 is divisible by 4.

    Required inputs: 'div4', 'div100'.
    Raises InputError for missing, undeclared, or non-bool inputs.
    """
    values = _checked_inputs(inputs, ("div4", "div100"), False)
    assumption_k2_value = _compute_assumption_k2(values["div4"], values["div100"])
    return assumption_k2_value
PostgreSQL
-- Tangibool PostgreSQL export (tangibool.postgresql/1)
-- Target: PostgreSQL 16 or later with typed boolean inputs; tested with PostgreSQL 18.3 (PGlite 0.5.8).
-- Not a claim of compatibility with other SQL dialects.
-- Model: not stated
-- Source revision: reference
-- Interpretation status: not stated
-- Exporter: 1.0.0 (engine 1.0.0; semantics tangibool-semantics/1)
-- Logic digest: 5469380ed02d1805f827fb98e06c6d3f30c3e855fe470b8e6e9fb099b023d732
-- Assumptions digest: c95d45363e428617061214db272f6ed6c809bda4bf8b9545d8c63b031323bc7c
-- Mode: decision
--
-- Read-only: this file contains only WITH / VALUES / SELECT statements. No DDL, DML,
-- procedures, credentials, network access, or database changes. The expressions are pure
-- Boolean expressions, so their result does not depend on SQL evaluation order.
--
-- NON-NULL INPUT PRECONDITION: NULL is not a truth value of this rule. Every fragment below
-- is defined only when every input column it reads is a non-NULL boolean. The guard template
-- (section 2) marks any NULL input as 'invalid_input' and any row that violates the
-- assumptions as 'out_of_scope', and fills output columns only for 'ok' rows; a NULL in an
-- output column of another row is an envelope marker, not a third truth value. Never wrap
-- the fragments in COALESCE(..., FALSE) or otherwise choose a meaning for unknown inputs.
-- This evaluates the supplied model; it does not show that the model is a complete, legal,
-- or safe statement of a real-world rule.
--
-- Input columns (stable ID: name -> column):
--   v_3b217ba27c75: div4 -> "in_div4"
--   v_e132c27d17cf: div100 -> "in_div100"
--   v_2440ffcf4122: div400 -> "in_div400"
-- Output columns:
--   f_46b25eaf9240: leap -> "out_leap"
-- Assumptions (scope K; exported separately and never folded into an output):
--   f_bdb57448a020: k1 -> "assumption_k1": div400 -> div100
--     A year divisible by 400 is divisible by 100.
--   f_c8cf788fb953: k2 -> "assumption_k2": div100 -> div4
--     A year divisible by 100 is divisible by 4.

-- ----------------------------------------------------------------------------------------------
-- 1. Expression fragments (parenthesised; non-NULL boolean inputs required)
-- ----------------------------------------------------------------------------------------------
--
-- [out_leap] output leap (stable ID f_46b25eaf9240)
--   leap := (div4 AND NOT div100) OR div400
--   PRECONDITION: "in_div4", "in_div100", "in_div400" are non-NULL booleans.
--   (("in_div4" AND (NOT "in_div100")) OR "in_div400")
--
-- [assumption_k1] assumption k1 (stable ID f_bdb57448a020)
--   k1 := div400 -> div100
--   PRECONDITION: "in_div100", "in_div400" are non-NULL booleans.
--   ((NOT "in_div400") OR "in_div100")
--
-- [assumption_k2] assumption k2 (stable ID f_c8cf788fb953)
--   k2 := div100 -> div4
--   PRECONDITION: "in_div4", "in_div100" are non-NULL booleans.
--   ((NOT "in_div100") OR "in_div4")
--
-- [K] scope (conjunction of the assumptions):
--   (((NOT "in_div400") OR "in_div100") AND ((NOT "in_div100") OR "in_div4"))
--

-- ----------------------------------------------------------------------------------------------
-- 2. Guard template (read-only SELECT over an inputs list)
-- ----------------------------------------------------------------------------------------------
-- Replace the example rows between the markers with your own rows, or replace the inputs
-- CTE with a SELECT that provides the boolean columns listed in the header. status is
-- 'invalid_input' when any input is NULL, 'out_of_scope' when the assumptions are false, and
-- 'ok' otherwise; output columns are filled only for 'ok' rows (NULL elsewhere is an
-- envelope marker). Assumption columns are shown for rows with complete inputs.
WITH inputs ("row_id", "in_div4", "in_div100", "in_div400") AS (
  -- tangibool:example-rows:begin
  VALUES
    (1, FALSE, FALSE, FALSE),
    (2, FALSE, FALSE, TRUE),
    (3, FALSE, TRUE, FALSE),
    (4, FALSE, TRUE, TRUE),
    (5, TRUE, FALSE, FALSE),
    (6, TRUE, FALSE, TRUE),
    (7, TRUE, TRUE, FALSE),
    (8, TRUE, TRUE, TRUE),
    (9, NULL::boolean, FALSE, FALSE)
  -- tangibool:example-rows:end
),
checked AS (
  SELECT
    inputs.*,
    CASE
      WHEN "in_div4" IS NULL OR "in_div100" IS NULL OR "in_div400" IS NULL THEN 'invalid_input'
      WHEN NOT (((NOT "in_div400") OR "in_div100") AND ((NOT "in_div100") OR "in_div4")) THEN 'out_of_scope'
      ELSE 'ok'
    END AS "status"
  FROM inputs
)
SELECT
  "row_id",
  "in_div4",
  "in_div100",
  "in_div400",
  "status",
  CASE WHEN "status" <> 'invalid_input' THEN ((NOT "in_div400") OR "in_div100") END AS "assumption_k1",
  CASE WHEN "status" <> 'invalid_input' THEN ((NOT "in_div100") OR "in_div4") END AS "assumption_k2",
  CASE WHEN "status" = 'ok' THEN (("in_div4" AND (NOT "in_div100")) OR "in_div400") END AS "out_leap"
FROM checked
ORDER BY "row_id";
SMT-LIB
; Tangibool SMT-LIB export (tangibool.smtlib/1)
; Profile: SMT-LIB 2.6 Boolean subset (QF_UF): Bool constants, define-fun, let, push/pop, assert, check-sat, echo.
; Tested with Z3 5.1.0 (z3-solver 5.2.0, WebAssembly build).
; Model: not stated
; Source revision: reference
; Interpretation status: not stated
; Exporter: 1.0.0 (engine 1.0.0; semantics tangibool-semantics/1)
; Logic digest: 5469380ed02d1805f827fb98e06c6d3f30c3e855fe470b8e6e9fb099b023d732
; Assumptions digest: c95d45363e428617061214db272f6ed6c809bda4bf8b9545d8c63b031323bc7c
; Mode: decision
;
; Reading results: each query block states what sat and unsat mean for its question. A sat
; answer comes with a witness or counterexample (ask for it with (get-model) after sat only);
; unsat settles that scoped query and is solver-checked, not an independently checked proof
; certificate; unknown settles nothing. Blocks are scoped with push/pop, so assertions never
; accumulate across questions. This checks the supplied model, not whether it is a complete,
; legal, or safe statement of a real-world rule.
;
; Symbols (stable ID: name -> symbol):
;   v_3b217ba27c75: div4 -> in_div4
;   v_e132c27d17cf: div100 -> in_div100
;   v_2440ffcf4122: div400 -> in_div400
;   f_46b25eaf9240: leap -> out_leap
;   f_bdb57448a020: k1 -> assumption_k1
;   f_c8cf788fb953: k2 -> assumption_k2

(set-option :produce-models true)
(set-info :smt-lib-version 2.6)
(set-logic QF_UF)

; ---- Inputs (declared order)
(declare-const in_div4 Bool) ; div4
(declare-const in_div100 Bool) ; div100
(declare-const in_div400 Bool) ; div400

; ---- Outputs (dependencies first)
; output leap (stable ID f_46b25eaf9240): (div4 AND NOT div100) OR div400
(define-fun out_leap () Bool (or (and in_div4 (not in_div100)) in_div400))

; ---- Assumptions (the scope K; never folded into an output)
; assumption k1 (stable ID f_bdb57448a020): div400 -> div100
;   A year divisible by 400 is divisible by 100.
(define-fun assumption_k1 () Bool (=> in_div400 in_div100))
; assumption k2 (stable ID f_c8cf788fb953): div100 -> div4
;   A year divisible by 100 is divisible by 4.
(define-fun assumption_k2 () Bool (=> in_div100 in_div4))
; K: conjunction of the enabled, confirmed assumptions (true when there are none)
(define-fun K () Bool (and assumption_k1 assumption_k2))

; ---- Definitions only: nothing is asserted and no check is run.
; Add (assert ...) and (check-sat) inside (push 1) ... (pop 1) to ask a question.
LaTeX
leap = \left(\mathit{div4} \cdot \overline{\mathit{div100}}\right) + \mathit{div400}

El error habitual

Simplificar la regla a div4 AND NOT div100 y olvidar el año 2000. En la fila 7, div4 = VERDADERO, div100 = VERDADERO, div400 = VERDADERO, la regla completa es verdadera y la acortada es falsa. Esa fila es posible bajo los dos supuestos, así que ninguna indiferencia excusa la omisión.

Preguntas

¿Por qué el mapa dice tres implicantes primos pero dibuja dos grupos?

Con las cuatro celdas de indiferencia disponibles, se puede formar un tercer grupo que la cobertura no necesita; los dos grupos dibujados ya cubren todas las celdas verdaderas. El motor informa del número que encontró y de la cobertura que usó, y etiqueta el resultado como válido dentro de los supuestos.

¿Se puede escribir la regla como una prueba directa sobre el año?

Sí, en código es year % 4 == 0 and year % 100 != 0 or year % 400 == 0, que es la misma fórmula con los indicadores calculados en línea. El Python exportado de la página evalúa los tres indicadores como entradas; conectarlos a la aritmética es tarea de quien llama.

Relacionado

Operadores y compuertas

Herramientas

Véase también

Ejemplos resueltos

Generado a partir del motor de Tangibool, semántica tangibool-semantics/1, motor 1.0.0, compilación . Cada tabla, mapa, simplificación y veredicto de estas páginas lo calculó el motor de Tangibool al compilar el sitio, y cada afirmación la volvió a comprobar el mismo verificador exacto que usa la app. Los límites se indican donde aplican. © 2026 Foreranger LTD.