/- Copyright 2026 The Formal Conjectures Authors. Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at https://www.apache.org/licenses/LICENSE-2.0 Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License. -/ module public import FormalConjecturesUtil

Taxicab numbers

A taxicab number for natural numbers $k, m, n$ is the smallest number $x$ that can be expressed as a sum of $m$ positive $k$-th powers in at least $n$ distinct ways. The most famous taxicab number is $ 1729 = 1³ + 12³ = 9³ + 10³, $ also known as the Hardy–Ramanujan number.

However, a taxicab number is not known for $k=5$, $m=2$, and any $n ≥ 2$: No positive integer is known that can be written as the sum of two 5th powers in more than one way, and it is not known whether such a number exists.

In particular, it is not known whether there exists a taxicab number for $k=5$, $m=2$, and $n=2$.

References:

@[expose] public sectionnamespace Taxicab

$x$ is a candidate for being a taxicab number for $k, m, n$ if there exist at least $n$ distinct multisets of $m$ positive integers such that the sum of the $k$-th powers of the elements of each multiset is $x$. Using multisets means that two representations that differ only in the order of their terms count as one way.

def IsTaxicabFor' (k m n x : ) : Prop := S : Finset (Multiset ), n S.card L S, Multiset.card L = m 0 L (L.map (· ^ k)).sum = x

$1729$ is a possible taxicab number for $k=3, m=2, n=2$.

@[category test, AMS 11] theorem taxicab_1729 : IsTaxicabFor' 3 2 2 1729 := IsTaxicabFor' 3 2 2 1729 2 {{1, 12}, {9, 10}}.card L {{1, 12}, {9, 10}}, L.card = 2 0 L (Multiset.map (fun x x ^ 3) L).sum = 1729 All goals completed! 🐙

$x$ is a taxicab number if it is the smallest number that can be expressed as a sum of $m$ positive $k$-th powers in at least $n$ distinct ways.

def IsTaxicabFor (k m n : ) (x : ) : Prop := IsLeast { x : | IsTaxicabFor' k m n x } x@[category test, AMS 11] theorem taxicab_4' : IsTaxicabFor' 1 2 2 4 := IsTaxicabFor' 1 2 2 4 2 {{1, 3}, {2, 2}}.card L {{1, 3}, {2, 2}}, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = 4 All goals completed! 🐙

$4$ is the taxicab number for $k=1, m=2, n=2$.

x:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:hs:{a, b} Shs₁:{a, b}.card = 2c:d:ht:{c, d} Sht₁:{c, d}.card = 2hst:{a, b} {c, d}hs₂:¬0 = a ¬0 = bht₂:¬0 = c ¬0 = dhs₃:a + b = xht₃:c + d = xh:¬4 xha:a 2hb:b 2hc:c 2hd:d 2False x:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:ht:{c, d} Sht₁:{c, d}.card = 2ht₂:¬0 = c ¬0 = dht₃:c + d = xh:¬4 xhb:b 2hc:c 2hd:d 2hs:{0, b} Shs₁:{0, b}.card = 2hst:{0, b} {c, d}hs₂:¬0 = 0 ¬0 = bhs₃:0 + b = xha:0 2Falsex:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:ht:{c, d} Sht₁:{c, d}.card = 2ht₂:¬0 = c ¬0 = dht₃:c + d = xh:¬4 xhb:b 2hc:c 2hd:d 2hs:{1, b} Shs₁:{1, b}.card = 2hst:{1, b} {c, d}hs₂:¬0 = 1 ¬0 = bhs₃:1 + b = xha:1 2Falsex:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:ht:{c, d} Sht₁:{c, d}.card = 2ht₂:¬0 = c ¬0 = dht₃:c + d = xh:¬4 xhb:b 2hc:c 2hd:d 2hs:{2, b} Shs₁:{2, b}.card = 2hst:{2, b} {c, d}hs₂:¬0 = 2 ¬0 = bhs₃:2 + b = xha:2 2False x:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:ht:{c, d} Sht₁:{c, d}.card = 2ht₂:¬0 = c ¬0 = dht₃:c + d = xh:¬4 xhb:b 2hc:c 2hd:d 2hs:{0, b} Shs₁:{0, b}.card = 2hst:{0, b} {c, d}hs₂:¬0 = 0 ¬0 = bhs₃:0 + b = xha:0 2Falsex:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:ht:{c, d} Sht₁:{c, d}.card = 2ht₂:¬0 = c ¬0 = dht₃:c + d = xh:¬4 xhb:b 2hc:c 2hd:d 2hs:{1, b} Shs₁:{1, b}.card = 2hst:{1, b} {c, d}hs₂:¬0 = 1 ¬0 = bhs₃:1 + b = xha:1 2Falsex:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:ht:{c, d} Sht₁:{c, d}.card = 2ht₂:¬0 = c ¬0 = dht₃:c + d = xh:¬4 xhb:b 2hc:c 2hd:d 2hs:{2, b} Shs₁:{2, b}.card = 2hst:{2, b} {c, d}hs₂:¬0 = 2 ¬0 = bhs₃:2 + b = xha:2 2False x:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:ht:{c, d} Sht₁:{c, d}.card = 2ht₂:¬0 = c ¬0 = dht₃:c + d = xh:¬4 xhc:c 2hd:d 2ha:2 2hb:0 2hs:{2, 0} Shs₁:{2, 0}.card = 2hst:{2, 0} {c, d}hs₂:¬0 = 2 ¬0 = 0hs₃:2 + 0 = xFalsex:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:ht:{c, d} Sht₁:{c, d}.card = 2ht₂:¬0 = c ¬0 = dht₃:c + d = xh:¬4 xhc:c 2hd:d 2ha:2 2hb:1 2hs:{2, 1} Shs₁:{2, 1}.card = 2hst:{2, 1} {c, d}hs₂:¬0 = 2 ¬0 = 1hs₃:2 + 1 = xFalsex:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:ht:{c, d} Sht₁:{c, d}.card = 2ht₂:¬0 = c ¬0 = dht₃:c + d = xh:¬4 xhc:c 2hd:d 2ha:2 2hb:2 2hs:{2, 2} Shs₁:{2, 2}.card = 2hst:{2, 2} {c, d}hs₂:¬0 = 2 ¬0 = 2hs₃:2 + 2 = xFalse x:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:ht:{c, d} Sht₁:{c, d}.card = 2ht₂:¬0 = c ¬0 = dht₃:c + d = xh:¬4 xhc:c 2hd:d 2ha:0 2hb:0 2hs:{0, 0} Shs₁:{0, 0}.card = 2hst:{0, 0} {c, d}hs₂:¬0 = 0 ¬0 = 0hs₃:0 + 0 = xFalsex:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:ht:{c, d} Sht₁:{c, d}.card = 2ht₂:¬0 = c ¬0 = dht₃:c + d = xh:¬4 xhc:c 2hd:d 2ha:0 2hb:1 2hs:{0, 1} Shs₁:{0, 1}.card = 2hst:{0, 1} {c, d}hs₂:¬0 = 0 ¬0 = 1hs₃:0 + 1 = xFalsex:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:ht:{c, d} Sht₁:{c, d}.card = 2ht₂:¬0 = c ¬0 = dht₃:c + d = xh:¬4 xhc:c 2hd:d 2ha:0 2hb:2 2hs:{0, 2} Shs₁:{0, 2}.card = 2hst:{0, 2} {c, d}hs₂:¬0 = 0 ¬0 = 2hs₃:0 + 2 = xFalsex:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:ht:{c, d} Sht₁:{c, d}.card = 2ht₂:¬0 = c ¬0 = dht₃:c + d = xh:¬4 xhc:c 2hd:d 2ha:1 2hb:0 2hs:{1, 0} Shs₁:{1, 0}.card = 2hst:{1, 0} {c, d}hs₂:¬0 = 1 ¬0 = 0hs₃:1 + 0 = xFalsex:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:ht:{c, d} Sht₁:{c, d}.card = 2ht₂:¬0 = c ¬0 = dht₃:c + d = xh:¬4 xhc:c 2hd:d 2ha:1 2hb:1 2hs:{1, 1} Shs₁:{1, 1}.card = 2hst:{1, 1} {c, d}hs₂:¬0 = 1 ¬0 = 1hs₃:1 + 1 = xFalsex:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:ht:{c, d} Sht₁:{c, d}.card = 2ht₂:¬0 = c ¬0 = dht₃:c + d = xh:¬4 xhc:c 2hd:d 2ha:1 2hb:2 2hs:{1, 2} Shs₁:{1, 2}.card = 2hst:{1, 2} {c, d}hs₂:¬0 = 1 ¬0 = 2hs₃:1 + 2 = xFalsex:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:ht:{c, d} Sht₁:{c, d}.card = 2ht₂:¬0 = c ¬0 = dht₃:c + d = xh:¬4 xhc:c 2hd:d 2ha:2 2hb:0 2hs:{2, 0} Shs₁:{2, 0}.card = 2hst:{2, 0} {c, d}hs₂:¬0 = 2 ¬0 = 0hs₃:2 + 0 = xFalsex:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:ht:{c, d} Sht₁:{c, d}.card = 2ht₂:¬0 = c ¬0 = dht₃:c + d = xh:¬4 xhc:c 2hd:d 2ha:2 2hb:1 2hs:{2, 1} Shs₁:{2, 1}.card = 2hst:{2, 1} {c, d}hs₂:¬0 = 2 ¬0 = 1hs₃:2 + 1 = xFalsex:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:ht:{c, d} Sht₁:{c, d}.card = 2ht₂:¬0 = c ¬0 = dht₃:c + d = xh:¬4 xhc:c 2hd:d 2ha:2 2hb:2 2hs:{2, 2} Shs₁:{2, 2}.card = 2hst:{2, 2} {c, d}hs₂:¬0 = 2 ¬0 = 2hs₃:2 + 2 = xFalse x:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:h:¬4 xhd:d 2ha:2 2hb:2 2hs:{2, 2} Shs₁:{2, 2}.card = 2hs₂:¬0 = 2 ¬0 = 2hs₃:2 + 2 = xht:{0, d} Sht₁:{0, d}.card = 2ht₂:¬0 = 0 ¬0 = dht₃:0 + d = xhc:0 2hst:{2, 2} {0, d}Falsex:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:h:¬4 xhd:d 2ha:2 2hb:2 2hs:{2, 2} Shs₁:{2, 2}.card = 2hs₂:¬0 = 2 ¬0 = 2hs₃:2 + 2 = xht:{1, d} Sht₁:{1, d}.card = 2ht₂:¬0 = 1 ¬0 = dht₃:1 + d = xhc:1 2hst:{2, 2} {1, d}Falsex:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:h:¬4 xhd:d 2ha:2 2hb:2 2hs:{2, 2} Shs₁:{2, 2}.card = 2hs₂:¬0 = 2 ¬0 = 2hs₃:2 + 2 = xht:{2, d} Sht₁:{2, d}.card = 2ht₂:¬0 = 2 ¬0 = dht₃:2 + d = xhc:2 2hst:{2, 2} {2, d}False x:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:h:¬4 xhd:d 2ha:0 2hb:0 2hs:{0, 0} Shs₁:{0, 0}.card = 2hs₂:¬0 = 0 ¬0 = 0hs₃:0 + 0 = xht:{0, d} Sht₁:{0, d}.card = 2ht₂:¬0 = 0 ¬0 = dht₃:0 + d = xhc:0 2hst:{0, 0} {0, d}Falsex:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:h:¬4 xhd:d 2ha:0 2hb:0 2hs:{0, 0} Shs₁:{0, 0}.card = 2hs₂:¬0 = 0 ¬0 = 0hs₃:0 + 0 = xht:{1, d} Sht₁:{1, d}.card = 2ht₂:¬0 = 1 ¬0 = dht₃:1 + d = xhc:1 2hst:{0, 0} {1, d}Falsex:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:h:¬4 xhd:d 2ha:0 2hb:0 2hs:{0, 0} Shs₁:{0, 0}.card = 2hs₂:¬0 = 0 ¬0 = 0hs₃:0 + 0 = xht:{2, d} Sht₁:{2, d}.card = 2ht₂:¬0 = 2 ¬0 = dht₃:2 + d = xhc:2 2hst:{0, 0} {2, d}Falsex:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:h:¬4 xhd:d 2ha:0 2hb:1 2hs:{0, 1} Shs₁:{0, 1}.card = 2hs₂:¬0 = 0 ¬0 = 1hs₃:0 + 1 = xht:{0, d} Sht₁:{0, d}.card = 2ht₂:¬0 = 0 ¬0 = dht₃:0 + d = xhc:0 2hst:{0, 1} {0, d}Falsex:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:h:¬4 xhd:d 2ha:0 2hb:1 2hs:{0, 1} Shs₁:{0, 1}.card = 2hs₂:¬0 = 0 ¬0 = 1hs₃:0 + 1 = xht:{1, d} Sht₁:{1, d}.card = 2ht₂:¬0 = 1 ¬0 = dht₃:1 + d = xhc:1 2hst:{0, 1} {1, d}Falsex:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:h:¬4 xhd:d 2ha:0 2hb:1 2hs:{0, 1} Shs₁:{0, 1}.card = 2hs₂:¬0 = 0 ¬0 = 1hs₃:0 + 1 = xht:{2, d} Sht₁:{2, d}.card = 2ht₂:¬0 = 2 ¬0 = dht₃:2 + d = xhc:2 2hst:{0, 1} {2, d}Falsex:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:h:¬4 xhd:d 2ha:0 2hb:2 2hs:{0, 2} Shs₁:{0, 2}.card = 2hs₂:¬0 = 0 ¬0 = 2hs₃:0 + 2 = xht:{0, d} Sht₁:{0, d}.card = 2ht₂:¬0 = 0 ¬0 = dht₃:0 + d = xhc:0 2hst:{0, 2} {0, d}Falsex:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:h:¬4 xhd:d 2ha:0 2hb:2 2hs:{0, 2} Shs₁:{0, 2}.card = 2hs₂:¬0 = 0 ¬0 = 2hs₃:0 + 2 = xht:{1, d} Sht₁:{1, d}.card = 2ht₂:¬0 = 1 ¬0 = dht₃:1 + d = xhc:1 2hst:{0, 2} {1, d}Falsex:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:h:¬4 xhd:d 2ha:0 2hb:2 2hs:{0, 2} Shs₁:{0, 2}.card = 2hs₂:¬0 = 0 ¬0 = 2hs₃:0 + 2 = xht:{2, d} Sht₁:{2, d}.card = 2ht₂:¬0 = 2 ¬0 = dht₃:2 + d = xhc:2 2hst:{0, 2} {2, d}Falsex:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:h:¬4 xhd:d 2ha:1 2hb:0 2hs:{1, 0} Shs₁:{1, 0}.card = 2hs₂:¬0 = 1 ¬0 = 0hs₃:1 + 0 = xht:{0, d} Sht₁:{0, d}.card = 2ht₂:¬0 = 0 ¬0 = dht₃:0 + d = xhc:0 2hst:{1, 0} {0, d}Falsex:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:h:¬4 xhd:d 2ha:1 2hb:0 2hs:{1, 0} Shs₁:{1, 0}.card = 2hs₂:¬0 = 1 ¬0 = 0hs₃:1 + 0 = xht:{1, d} Sht₁:{1, d}.card = 2ht₂:¬0 = 1 ¬0 = dht₃:1 + d = xhc:1 2hst:{1, 0} {1, d}Falsex:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:h:¬4 xhd:d 2ha:1 2hb:0 2hs:{1, 0} Shs₁:{1, 0}.card = 2hs₂:¬0 = 1 ¬0 = 0hs₃:1 + 0 = xht:{2, d} Sht₁:{2, d}.card = 2ht₂:¬0 = 2 ¬0 = dht₃:2 + d = xhc:2 2hst:{1, 0} {2, d}Falsex:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:h:¬4 xhd:d 2ha:1 2hb:1 2hs:{1, 1} Shs₁:{1, 1}.card = 2hs₂:¬0 = 1 ¬0 = 1hs₃:1 + 1 = xht:{0, d} Sht₁:{0, d}.card = 2ht₂:¬0 = 0 ¬0 = dht₃:0 + d = xhc:0 2hst:{1, 1} {0, d}Falsex:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:h:¬4 xhd:d 2ha:1 2hb:1 2hs:{1, 1} Shs₁:{1, 1}.card = 2hs₂:¬0 = 1 ¬0 = 1hs₃:1 + 1 = xht:{1, d} Sht₁:{1, d}.card = 2ht₂:¬0 = 1 ¬0 = dht₃:1 + d = xhc:1 2hst:{1, 1} {1, d}Falsex:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:h:¬4 xhd:d 2ha:1 2hb:1 2hs:{1, 1} Shs₁:{1, 1}.card = 2hs₂:¬0 = 1 ¬0 = 1hs₃:1 + 1 = xht:{2, d} Sht₁:{2, d}.card = 2ht₂:¬0 = 2 ¬0 = dht₃:2 + d = xhc:2 2hst:{1, 1} {2, d}Falsex:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:h:¬4 xhd:d 2ha:1 2hb:2 2hs:{1, 2} Shs₁:{1, 2}.card = 2hs₂:¬0 = 1 ¬0 = 2hs₃:1 + 2 = xht:{0, d} Sht₁:{0, d}.card = 2ht₂:¬0 = 0 ¬0 = dht₃:0 + d = xhc:0 2hst:{1, 2} {0, d}Falsex:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:h:¬4 xhd:d 2ha:1 2hb:2 2hs:{1, 2} Shs₁:{1, 2}.card = 2hs₂:¬0 = 1 ¬0 = 2hs₃:1 + 2 = xht:{1, d} Sht₁:{1, d}.card = 2ht₂:¬0 = 1 ¬0 = dht₃:1 + d = xhc:1 2hst:{1, 2} {1, d}Falsex:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:h:¬4 xhd:d 2ha:1 2hb:2 2hs:{1, 2} Shs₁:{1, 2}.card = 2hs₂:¬0 = 1 ¬0 = 2hs₃:1 + 2 = xht:{2, d} Sht₁:{2, d}.card = 2ht₂:¬0 = 2 ¬0 = dht₃:2 + d = xhc:2 2hst:{1, 2} {2, d}Falsex:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:h:¬4 xhd:d 2ha:2 2hb:0 2hs:{2, 0} Shs₁:{2, 0}.card = 2hs₂:¬0 = 2 ¬0 = 0hs₃:2 + 0 = xht:{0, d} Sht₁:{0, d}.card = 2ht₂:¬0 = 0 ¬0 = dht₃:0 + d = xhc:0 2hst:{2, 0} {0, d}Falsex:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:h:¬4 xhd:d 2ha:2 2hb:0 2hs:{2, 0} Shs₁:{2, 0}.card = 2hs₂:¬0 = 2 ¬0 = 0hs₃:2 + 0 = xht:{1, d} Sht₁:{1, d}.card = 2ht₂:¬0 = 1 ¬0 = dht₃:1 + d = xhc:1 2hst:{2, 0} {1, d}Falsex:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:h:¬4 xhd:d 2ha:2 2hb:0 2hs:{2, 0} Shs₁:{2, 0}.card = 2hs₂:¬0 = 2 ¬0 = 0hs₃:2 + 0 = xht:{2, d} Sht₁:{2, d}.card = 2ht₂:¬0 = 2 ¬0 = dht₃:2 + d = xhc:2 2hst:{2, 0} {2, d}Falsex:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:h:¬4 xhd:d 2ha:2 2hb:1 2hs:{2, 1} Shs₁:{2, 1}.card = 2hs₂:¬0 = 2 ¬0 = 1hs₃:2 + 1 = xht:{0, d} Sht₁:{0, d}.card = 2ht₂:¬0 = 0 ¬0 = dht₃:0 + d = xhc:0 2hst:{2, 1} {0, d}Falsex:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:h:¬4 xhd:d 2ha:2 2hb:1 2hs:{2, 1} Shs₁:{2, 1}.card = 2hs₂:¬0 = 2 ¬0 = 1hs₃:2 + 1 = xht:{1, d} Sht₁:{1, d}.card = 2ht₂:¬0 = 1 ¬0 = dht₃:1 + d = xhc:1 2hst:{2, 1} {1, d}Falsex:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:h:¬4 xhd:d 2ha:2 2hb:1 2hs:{2, 1} Shs₁:{2, 1}.card = 2hs₂:¬0 = 2 ¬0 = 1hs₃:2 + 1 = xht:{2, d} Sht₁:{2, d}.card = 2ht₂:¬0 = 2 ¬0 = dht₃:2 + d = xhc:2 2hst:{2, 1} {2, d}Falsex:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:h:¬4 xhd:d 2ha:2 2hb:2 2hs:{2, 2} Shs₁:{2, 2}.card = 2hs₂:¬0 = 2 ¬0 = 2hs₃:2 + 2 = xht:{0, d} Sht₁:{0, d}.card = 2ht₂:¬0 = 0 ¬0 = dht₃:0 + d = xhc:0 2hst:{2, 2} {0, d}Falsex:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:h:¬4 xhd:d 2ha:2 2hb:2 2hs:{2, 2} Shs₁:{2, 2}.card = 2hs₂:¬0 = 2 ¬0 = 2hs₃:2 + 2 = xht:{1, d} Sht₁:{1, d}.card = 2ht₂:¬0 = 1 ¬0 = dht₃:1 + d = xhc:1 2hst:{2, 2} {1, d}Falsex:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:h:¬4 xhd:d 2ha:2 2hb:2 2hs:{2, 2} Shs₁:{2, 2}.card = 2hs₂:¬0 = 2 ¬0 = 2hs₃:2 + 2 = xht:{2, d} Sht₁:{2, d}.card = 2ht₂:¬0 = 2 ¬0 = dht₃:2 + d = xhc:2 2hst:{2, 2} {2, d}False x:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:h:¬4 xha:2 2hb:2 2hs:{2, 2} Shs₁:{2, 2}.card = 2hs₂:¬0 = 2 ¬0 = 2hs₃:2 + 2 = xhc:2 2hd:0 2ht:{2, 0} Sht₁:{2, 0}.card = 2ht₂:¬0 = 2 ¬0 = 0ht₃:2 + 0 = xhst:{2, 2} {2, 0}Falsex:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:h:¬4 xha:2 2hb:2 2hs:{2, 2} Shs₁:{2, 2}.card = 2hs₂:¬0 = 2 ¬0 = 2hs₃:2 + 2 = xhc:2 2hd:1 2ht:{2, 1} Sht₁:{2, 1}.card = 2ht₂:¬0 = 2 ¬0 = 1ht₃:2 + 1 = xhst:{2, 2} {2, 1}Falsex:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:h:¬4 xha:2 2hb:2 2hs:{2, 2} Shs₁:{2, 2}.card = 2hs₂:¬0 = 2 ¬0 = 2hs₃:2 + 2 = xhc:2 2hd:2 2ht:{2, 2} Sht₁:{2, 2}.card = 2ht₂:¬0 = 2 ¬0 = 2ht₃:2 + 2 = xhst:{2, 2} {2, 2}False x:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:h:¬4 xha:0 2hb:0 2hs:{0, 0} Shs₁:{0, 0}.card = 2hs₂:¬0 = 0 ¬0 = 0hs₃:0 + 0 = xhc:0 2hd:0 2ht:{0, 0} Sht₁:{0, 0}.card = 2ht₂:¬0 = 0 ¬0 = 0ht₃:0 + 0 = xhst:{0, 0} {0, 0}Falsex:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:h:¬4 xha:0 2hb:0 2hs:{0, 0} Shs₁:{0, 0}.card = 2hs₂:¬0 = 0 ¬0 = 0hs₃:0 + 0 = xhc:0 2hd:1 2ht:{0, 1} Sht₁:{0, 1}.card = 2ht₂:¬0 = 0 ¬0 = 1ht₃:0 + 1 = xhst:{0, 0} {0, 1}Falsex:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:h:¬4 xha:0 2hb:0 2hs:{0, 0} Shs₁:{0, 0}.card = 2hs₂:¬0 = 0 ¬0 = 0hs₃:0 + 0 = xhc:0 2hd:2 2ht:{0, 2} Sht₁:{0, 2}.card = 2ht₂:¬0 = 0 ¬0 = 2ht₃:0 + 2 = xhst:{0, 0} {0, 2}Falsex:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:h:¬4 xha:0 2hb:0 2hs:{0, 0} Shs₁:{0, 0}.card = 2hs₂:¬0 = 0 ¬0 = 0hs₃:0 + 0 = xhc:1 2hd:0 2ht:{1, 0} Sht₁:{1, 0}.card = 2ht₂:¬0 = 1 ¬0 = 0ht₃:1 + 0 = xhst:{0, 0} {1, 0}Falsex:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:h:¬4 xha:0 2hb:0 2hs:{0, 0} Shs₁:{0, 0}.card = 2hs₂:¬0 = 0 ¬0 = 0hs₃:0 + 0 = xhc:1 2hd:1 2ht:{1, 1} Sht₁:{1, 1}.card = 2ht₂:¬0 = 1 ¬0 = 1ht₃:1 + 1 = xhst:{0, 0} {1, 1}Falsex:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:h:¬4 xha:0 2hb:0 2hs:{0, 0} Shs₁:{0, 0}.card = 2hs₂:¬0 = 0 ¬0 = 0hs₃:0 + 0 = xhc:1 2hd:2 2ht:{1, 2} Sht₁:{1, 2}.card = 2ht₂:¬0 = 1 ¬0 = 2ht₃:1 + 2 = xhst:{0, 0} {1, 2}Falsex:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:h:¬4 xha:0 2hb:0 2hs:{0, 0} Shs₁:{0, 0}.card = 2hs₂:¬0 = 0 ¬0 = 0hs₃:0 + 0 = xhc:2 2hd:0 2ht:{2, 0} Sht₁:{2, 0}.card = 2ht₂:¬0 = 2 ¬0 = 0ht₃:2 + 0 = xhst:{0, 0} {2, 0}Falsex:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:h:¬4 xha:0 2hb:0 2hs:{0, 0} Shs₁:{0, 0}.card = 2hs₂:¬0 = 0 ¬0 = 0hs₃:0 + 0 = xhc:2 2hd:1 2ht:{2, 1} Sht₁:{2, 1}.card = 2ht₂:¬0 = 2 ¬0 = 1ht₃:2 + 1 = xhst:{0, 0} {2, 1}Falsex:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:h:¬4 xha:0 2hb:0 2hs:{0, 0} Shs₁:{0, 0}.card = 2hs₂:¬0 = 0 ¬0 = 0hs₃:0 + 0 = xhc:2 2hd:2 2ht:{2, 2} Sht₁:{2, 2}.card = 2ht₂:¬0 = 2 ¬0 = 2ht₃:2 + 2 = xhst:{0, 0} {2, 2}Falsex:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:h:¬4 xha:0 2hb:1 2hs:{0, 1} Shs₁:{0, 1}.card = 2hs₂:¬0 = 0 ¬0 = 1hs₃:0 + 1 = xhc:0 2hd:0 2ht:{0, 0} Sht₁:{0, 0}.card = 2ht₂:¬0 = 0 ¬0 = 0ht₃:0 + 0 = xhst:{0, 1} {0, 0}Falsex:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:h:¬4 xha:0 2hb:1 2hs:{0, 1} Shs₁:{0, 1}.card = 2hs₂:¬0 = 0 ¬0 = 1hs₃:0 + 1 = xhc:0 2hd:1 2ht:{0, 1} Sht₁:{0, 1}.card = 2ht₂:¬0 = 0 ¬0 = 1ht₃:0 + 1 = xhst:{0, 1} {0, 1}Falsex:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:h:¬4 xha:0 2hb:1 2hs:{0, 1} Shs₁:{0, 1}.card = 2hs₂:¬0 = 0 ¬0 = 1hs₃:0 + 1 = xhc:0 2hd:2 2ht:{0, 2} Sht₁:{0, 2}.card = 2ht₂:¬0 = 0 ¬0 = 2ht₃:0 + 2 = xhst:{0, 1} {0, 2}Falsex:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:h:¬4 xha:0 2hb:1 2hs:{0, 1} Shs₁:{0, 1}.card = 2hs₂:¬0 = 0 ¬0 = 1hs₃:0 + 1 = xhc:1 2hd:0 2ht:{1, 0} Sht₁:{1, 0}.card = 2ht₂:¬0 = 1 ¬0 = 0ht₃:1 + 0 = xhst:{0, 1} {1, 0}Falsex:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:h:¬4 xha:0 2hb:1 2hs:{0, 1} Shs₁:{0, 1}.card = 2hs₂:¬0 = 0 ¬0 = 1hs₃:0 + 1 = xhc:1 2hd:1 2ht:{1, 1} Sht₁:{1, 1}.card = 2ht₂:¬0 = 1 ¬0 = 1ht₃:1 + 1 = xhst:{0, 1} {1, 1}Falsex:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:h:¬4 xha:0 2hb:1 2hs:{0, 1} Shs₁:{0, 1}.card = 2hs₂:¬0 = 0 ¬0 = 1hs₃:0 + 1 = xhc:1 2hd:2 2ht:{1, 2} Sht₁:{1, 2}.card = 2ht₂:¬0 = 1 ¬0 = 2ht₃:1 + 2 = xhst:{0, 1} {1, 2}Falsex:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:h:¬4 xha:0 2hb:1 2hs:{0, 1} Shs₁:{0, 1}.card = 2hs₂:¬0 = 0 ¬0 = 1hs₃:0 + 1 = xhc:2 2hd:0 2ht:{2, 0} Sht₁:{2, 0}.card = 2ht₂:¬0 = 2 ¬0 = 0ht₃:2 + 0 = xhst:{0, 1} {2, 0}Falsex:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:h:¬4 xha:0 2hb:1 2hs:{0, 1} Shs₁:{0, 1}.card = 2hs₂:¬0 = 0 ¬0 = 1hs₃:0 + 1 = xhc:2 2hd:1 2ht:{2, 1} Sht₁:{2, 1}.card = 2ht₂:¬0 = 2 ¬0 = 1ht₃:2 + 1 = xhst:{0, 1} {2, 1}Falsex:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:h:¬4 xha:0 2hb:1 2hs:{0, 1} Shs₁:{0, 1}.card = 2hs₂:¬0 = 0 ¬0 = 1hs₃:0 + 1 = xhc:2 2hd:2 2ht:{2, 2} Sht₁:{2, 2}.card = 2ht₂:¬0 = 2 ¬0 = 2ht₃:2 + 2 = xhst:{0, 1} {2, 2}Falsex:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:h:¬4 xha:0 2hb:2 2hs:{0, 2} Shs₁:{0, 2}.card = 2hs₂:¬0 = 0 ¬0 = 2hs₃:0 + 2 = xhc:0 2hd:0 2ht:{0, 0} Sht₁:{0, 0}.card = 2ht₂:¬0 = 0 ¬0 = 0ht₃:0 + 0 = xhst:{0, 2} {0, 0}Falsex:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:h:¬4 xha:0 2hb:2 2hs:{0, 2} Shs₁:{0, 2}.card = 2hs₂:¬0 = 0 ¬0 = 2hs₃:0 + 2 = xhc:0 2hd:1 2ht:{0, 1} Sht₁:{0, 1}.card = 2ht₂:¬0 = 0 ¬0 = 1ht₃:0 + 1 = xhst:{0, 2} {0, 1}Falsex:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:h:¬4 xha:0 2hb:2 2hs:{0, 2} Shs₁:{0, 2}.card = 2hs₂:¬0 = 0 ¬0 = 2hs₃:0 + 2 = xhc:0 2hd:2 2ht:{0, 2} Sht₁:{0, 2}.card = 2ht₂:¬0 = 0 ¬0 = 2ht₃:0 + 2 = xhst:{0, 2} {0, 2}Falsex:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:h:¬4 xha:0 2hb:2 2hs:{0, 2} Shs₁:{0, 2}.card = 2hs₂:¬0 = 0 ¬0 = 2hs₃:0 + 2 = xhc:1 2hd:0 2ht:{1, 0} Sht₁:{1, 0}.card = 2ht₂:¬0 = 1 ¬0 = 0ht₃:1 + 0 = xhst:{0, 2} {1, 0}Falsex:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:h:¬4 xha:0 2hb:2 2hs:{0, 2} Shs₁:{0, 2}.card = 2hs₂:¬0 = 0 ¬0 = 2hs₃:0 + 2 = xhc:1 2hd:1 2ht:{1, 1} Sht₁:{1, 1}.card = 2ht₂:¬0 = 1 ¬0 = 1ht₃:1 + 1 = xhst:{0, 2} {1, 1}Falsex:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:h:¬4 xha:0 2hb:2 2hs:{0, 2} Shs₁:{0, 2}.card = 2hs₂:¬0 = 0 ¬0 = 2hs₃:0 + 2 = xhc:1 2hd:2 2ht:{1, 2} Sht₁:{1, 2}.card = 2ht₂:¬0 = 1 ¬0 = 2ht₃:1 + 2 = xhst:{0, 2} {1, 2}Falsex:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:h:¬4 xha:0 2hb:2 2hs:{0, 2} Shs₁:{0, 2}.card = 2hs₂:¬0 = 0 ¬0 = 2hs₃:0 + 2 = xhc:2 2hd:0 2ht:{2, 0} Sht₁:{2, 0}.card = 2ht₂:¬0 = 2 ¬0 = 0ht₃:2 + 0 = xhst:{0, 2} {2, 0}Falsex:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:h:¬4 xha:0 2hb:2 2hs:{0, 2} Shs₁:{0, 2}.card = 2hs₂:¬0 = 0 ¬0 = 2hs₃:0 + 2 = xhc:2 2hd:1 2ht:{2, 1} Sht₁:{2, 1}.card = 2ht₂:¬0 = 2 ¬0 = 1ht₃:2 + 1 = xhst:{0, 2} {2, 1}Falsex:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:h:¬4 xha:0 2hb:2 2hs:{0, 2} Shs₁:{0, 2}.card = 2hs₂:¬0 = 0 ¬0 = 2hs₃:0 + 2 = xhc:2 2hd:2 2ht:{2, 2} Sht₁:{2, 2}.card = 2ht₂:¬0 = 2 ¬0 = 2ht₃:2 + 2 = xhst:{0, 2} {2, 2}Falsex:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:h:¬4 xha:1 2hb:0 2hs:{1, 0} Shs₁:{1, 0}.card = 2hs₂:¬0 = 1 ¬0 = 0hs₃:1 + 0 = xhc:0 2hd:0 2ht:{0, 0} Sht₁:{0, 0}.card = 2ht₂:¬0 = 0 ¬0 = 0ht₃:0 + 0 = xhst:{1, 0} {0, 0}Falsex:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:h:¬4 xha:1 2hb:0 2hs:{1, 0} Shs₁:{1, 0}.card = 2hs₂:¬0 = 1 ¬0 = 0hs₃:1 + 0 = xhc:0 2hd:1 2ht:{0, 1} Sht₁:{0, 1}.card = 2ht₂:¬0 = 0 ¬0 = 1ht₃:0 + 1 = xhst:{1, 0} {0, 1}Falsex:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:h:¬4 xha:1 2hb:0 2hs:{1, 0} Shs₁:{1, 0}.card = 2hs₂:¬0 = 1 ¬0 = 0hs₃:1 + 0 = xhc:0 2hd:2 2ht:{0, 2} Sht₁:{0, 2}.card = 2ht₂:¬0 = 0 ¬0 = 2ht₃:0 + 2 = xhst:{1, 0} {0, 2}Falsex:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:h:¬4 xha:1 2hb:0 2hs:{1, 0} Shs₁:{1, 0}.card = 2hs₂:¬0 = 1 ¬0 = 0hs₃:1 + 0 = xhc:1 2hd:0 2ht:{1, 0} Sht₁:{1, 0}.card = 2ht₂:¬0 = 1 ¬0 = 0ht₃:1 + 0 = xhst:{1, 0} {1, 0}Falsex:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:h:¬4 xha:1 2hb:0 2hs:{1, 0} Shs₁:{1, 0}.card = 2hs₂:¬0 = 1 ¬0 = 0hs₃:1 + 0 = xhc:1 2hd:1 2ht:{1, 1} Sht₁:{1, 1}.card = 2ht₂:¬0 = 1 ¬0 = 1ht₃:1 + 1 = xhst:{1, 0} {1, 1}Falsex:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:h:¬4 xha:1 2hb:0 2hs:{1, 0} Shs₁:{1, 0}.card = 2hs₂:¬0 = 1 ¬0 = 0hs₃:1 + 0 = xhc:1 2hd:2 2ht:{1, 2} Sht₁:{1, 2}.card = 2ht₂:¬0 = 1 ¬0 = 2ht₃:1 + 2 = xhst:{1, 0} {1, 2}Falsex:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:h:¬4 xha:1 2hb:0 2hs:{1, 0} Shs₁:{1, 0}.card = 2hs₂:¬0 = 1 ¬0 = 0hs₃:1 + 0 = xhc:2 2hd:0 2ht:{2, 0} Sht₁:{2, 0}.card = 2ht₂:¬0 = 2 ¬0 = 0ht₃:2 + 0 = xhst:{1, 0} {2, 0}Falsex:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:h:¬4 xha:1 2hb:0 2hs:{1, 0} Shs₁:{1, 0}.card = 2hs₂:¬0 = 1 ¬0 = 0hs₃:1 + 0 = xhc:2 2hd:1 2ht:{2, 1} Sht₁:{2, 1}.card = 2ht₂:¬0 = 2 ¬0 = 1ht₃:2 + 1 = xhst:{1, 0} {2, 1}Falsex:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:h:¬4 xha:1 2hb:0 2hs:{1, 0} Shs₁:{1, 0}.card = 2hs₂:¬0 = 1 ¬0 = 0hs₃:1 + 0 = xhc:2 2hd:2 2ht:{2, 2} Sht₁:{2, 2}.card = 2ht₂:¬0 = 2 ¬0 = 2ht₃:2 + 2 = xhst:{1, 0} {2, 2}Falsex:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:h:¬4 xha:1 2hb:1 2hs:{1, 1} Shs₁:{1, 1}.card = 2hs₂:¬0 = 1 ¬0 = 1hs₃:1 + 1 = xhc:0 2hd:0 2ht:{0, 0} Sht₁:{0, 0}.card = 2ht₂:¬0 = 0 ¬0 = 0ht₃:0 + 0 = xhst:{1, 1} {0, 0}Falsex:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:h:¬4 xha:1 2hb:1 2hs:{1, 1} Shs₁:{1, 1}.card = 2hs₂:¬0 = 1 ¬0 = 1hs₃:1 + 1 = xhc:0 2hd:1 2ht:{0, 1} Sht₁:{0, 1}.card = 2ht₂:¬0 = 0 ¬0 = 1ht₃:0 + 1 = xhst:{1, 1} {0, 1}Falsex:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:h:¬4 xha:1 2hb:1 2hs:{1, 1} Shs₁:{1, 1}.card = 2hs₂:¬0 = 1 ¬0 = 1hs₃:1 + 1 = xhc:0 2hd:2 2ht:{0, 2} Sht₁:{0, 2}.card = 2ht₂:¬0 = 0 ¬0 = 2ht₃:0 + 2 = xhst:{1, 1} {0, 2}Falsex:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:h:¬4 xha:1 2hb:1 2hs:{1, 1} Shs₁:{1, 1}.card = 2hs₂:¬0 = 1 ¬0 = 1hs₃:1 + 1 = xhc:1 2hd:0 2ht:{1, 0} Sht₁:{1, 0}.card = 2ht₂:¬0 = 1 ¬0 = 0ht₃:1 + 0 = xhst:{1, 1} {1, 0}Falsex:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:h:¬4 xha:1 2hb:1 2hs:{1, 1} Shs₁:{1, 1}.card = 2hs₂:¬0 = 1 ¬0 = 1hs₃:1 + 1 = xhc:1 2hd:1 2ht:{1, 1} Sht₁:{1, 1}.card = 2ht₂:¬0 = 1 ¬0 = 1ht₃:1 + 1 = xhst:{1, 1} {1, 1}Falsex:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:h:¬4 xha:1 2hb:1 2hs:{1, 1} Shs₁:{1, 1}.card = 2hs₂:¬0 = 1 ¬0 = 1hs₃:1 + 1 = xhc:1 2hd:2 2ht:{1, 2} Sht₁:{1, 2}.card = 2ht₂:¬0 = 1 ¬0 = 2ht₃:1 + 2 = xhst:{1, 1} {1, 2}Falsex:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:h:¬4 xha:1 2hb:1 2hs:{1, 1} Shs₁:{1, 1}.card = 2hs₂:¬0 = 1 ¬0 = 1hs₃:1 + 1 = xhc:2 2hd:0 2ht:{2, 0} Sht₁:{2, 0}.card = 2ht₂:¬0 = 2 ¬0 = 0ht₃:2 + 0 = xhst:{1, 1} {2, 0}Falsex:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:h:¬4 xha:1 2hb:1 2hs:{1, 1} Shs₁:{1, 1}.card = 2hs₂:¬0 = 1 ¬0 = 1hs₃:1 + 1 = xhc:2 2hd:1 2ht:{2, 1} Sht₁:{2, 1}.card = 2ht₂:¬0 = 2 ¬0 = 1ht₃:2 + 1 = xhst:{1, 1} {2, 1}Falsex:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:h:¬4 xha:1 2hb:1 2hs:{1, 1} Shs₁:{1, 1}.card = 2hs₂:¬0 = 1 ¬0 = 1hs₃:1 + 1 = xhc:2 2hd:2 2ht:{2, 2} Sht₁:{2, 2}.card = 2ht₂:¬0 = 2 ¬0 = 2ht₃:2 + 2 = xhst:{1, 1} {2, 2}Falsex:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:h:¬4 xha:1 2hb:2 2hs:{1, 2} Shs₁:{1, 2}.card = 2hs₂:¬0 = 1 ¬0 = 2hs₃:1 + 2 = xhc:0 2hd:0 2ht:{0, 0} Sht₁:{0, 0}.card = 2ht₂:¬0 = 0 ¬0 = 0ht₃:0 + 0 = xhst:{1, 2} {0, 0}Falsex:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:h:¬4 xha:1 2hb:2 2hs:{1, 2} Shs₁:{1, 2}.card = 2hs₂:¬0 = 1 ¬0 = 2hs₃:1 + 2 = xhc:0 2hd:1 2ht:{0, 1} Sht₁:{0, 1}.card = 2ht₂:¬0 = 0 ¬0 = 1ht₃:0 + 1 = xhst:{1, 2} {0, 1}Falsex:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:h:¬4 xha:1 2hb:2 2hs:{1, 2} Shs₁:{1, 2}.card = 2hs₂:¬0 = 1 ¬0 = 2hs₃:1 + 2 = xhc:0 2hd:2 2ht:{0, 2} Sht₁:{0, 2}.card = 2ht₂:¬0 = 0 ¬0 = 2ht₃:0 + 2 = xhst:{1, 2} {0, 2}Falsex:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:h:¬4 xha:1 2hb:2 2hs:{1, 2} Shs₁:{1, 2}.card = 2hs₂:¬0 = 1 ¬0 = 2hs₃:1 + 2 = xhc:1 2hd:0 2ht:{1, 0} Sht₁:{1, 0}.card = 2ht₂:¬0 = 1 ¬0 = 0ht₃:1 + 0 = xhst:{1, 2} {1, 0}Falsex:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:h:¬4 xha:1 2hb:2 2hs:{1, 2} Shs₁:{1, 2}.card = 2hs₂:¬0 = 1 ¬0 = 2hs₃:1 + 2 = xhc:1 2hd:1 2ht:{1, 1} Sht₁:{1, 1}.card = 2ht₂:¬0 = 1 ¬0 = 1ht₃:1 + 1 = xhst:{1, 2} {1, 1}Falsex:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:h:¬4 xha:1 2hb:2 2hs:{1, 2} Shs₁:{1, 2}.card = 2hs₂:¬0 = 1 ¬0 = 2hs₃:1 + 2 = xhc:1 2hd:2 2ht:{1, 2} Sht₁:{1, 2}.card = 2ht₂:¬0 = 1 ¬0 = 2ht₃:1 + 2 = xhst:{1, 2} {1, 2}Falsex:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:h:¬4 xha:1 2hb:2 2hs:{1, 2} Shs₁:{1, 2}.card = 2hs₂:¬0 = 1 ¬0 = 2hs₃:1 + 2 = xhc:2 2hd:0 2ht:{2, 0} Sht₁:{2, 0}.card = 2ht₂:¬0 = 2 ¬0 = 0ht₃:2 + 0 = xhst:{1, 2} {2, 0}Falsex:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:h:¬4 xha:1 2hb:2 2hs:{1, 2} Shs₁:{1, 2}.card = 2hs₂:¬0 = 1 ¬0 = 2hs₃:1 + 2 = xhc:2 2hd:1 2ht:{2, 1} Sht₁:{2, 1}.card = 2ht₂:¬0 = 2 ¬0 = 1ht₃:2 + 1 = xhst:{1, 2} {2, 1}Falsex:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:h:¬4 xha:1 2hb:2 2hs:{1, 2} Shs₁:{1, 2}.card = 2hs₂:¬0 = 1 ¬0 = 2hs₃:1 + 2 = xhc:2 2hd:2 2ht:{2, 2} Sht₁:{2, 2}.card = 2ht₂:¬0 = 2 ¬0 = 2ht₃:2 + 2 = xhst:{1, 2} {2, 2}Falsex:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:h:¬4 xha:2 2hb:0 2hs:{2, 0} Shs₁:{2, 0}.card = 2hs₂:¬0 = 2 ¬0 = 0hs₃:2 + 0 = xhc:0 2hd:0 2ht:{0, 0} Sht₁:{0, 0}.card = 2ht₂:¬0 = 0 ¬0 = 0ht₃:0 + 0 = xhst:{2, 0} {0, 0}Falsex:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:h:¬4 xha:2 2hb:0 2hs:{2, 0} Shs₁:{2, 0}.card = 2hs₂:¬0 = 2 ¬0 = 0hs₃:2 + 0 = xhc:0 2hd:1 2ht:{0, 1} Sht₁:{0, 1}.card = 2ht₂:¬0 = 0 ¬0 = 1ht₃:0 + 1 = xhst:{2, 0} {0, 1}Falsex:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:h:¬4 xha:2 2hb:0 2hs:{2, 0} Shs₁:{2, 0}.card = 2hs₂:¬0 = 2 ¬0 = 0hs₃:2 + 0 = xhc:0 2hd:2 2ht:{0, 2} Sht₁:{0, 2}.card = 2ht₂:¬0 = 0 ¬0 = 2ht₃:0 + 2 = xhst:{2, 0} {0, 2}Falsex:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:h:¬4 xha:2 2hb:0 2hs:{2, 0} Shs₁:{2, 0}.card = 2hs₂:¬0 = 2 ¬0 = 0hs₃:2 + 0 = xhc:1 2hd:0 2ht:{1, 0} Sht₁:{1, 0}.card = 2ht₂:¬0 = 1 ¬0 = 0ht₃:1 + 0 = xhst:{2, 0} {1, 0}Falsex:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:h:¬4 xha:2 2hb:0 2hs:{2, 0} Shs₁:{2, 0}.card = 2hs₂:¬0 = 2 ¬0 = 0hs₃:2 + 0 = xhc:1 2hd:1 2ht:{1, 1} Sht₁:{1, 1}.card = 2ht₂:¬0 = 1 ¬0 = 1ht₃:1 + 1 = xhst:{2, 0} {1, 1}Falsex:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:h:¬4 xha:2 2hb:0 2hs:{2, 0} Shs₁:{2, 0}.card = 2hs₂:¬0 = 2 ¬0 = 0hs₃:2 + 0 = xhc:1 2hd:2 2ht:{1, 2} Sht₁:{1, 2}.card = 2ht₂:¬0 = 1 ¬0 = 2ht₃:1 + 2 = xhst:{2, 0} {1, 2}Falsex:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:h:¬4 xha:2 2hb:0 2hs:{2, 0} Shs₁:{2, 0}.card = 2hs₂:¬0 = 2 ¬0 = 0hs₃:2 + 0 = xhc:2 2hd:0 2ht:{2, 0} Sht₁:{2, 0}.card = 2ht₂:¬0 = 2 ¬0 = 0ht₃:2 + 0 = xhst:{2, 0} {2, 0}Falsex:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:h:¬4 xha:2 2hb:0 2hs:{2, 0} Shs₁:{2, 0}.card = 2hs₂:¬0 = 2 ¬0 = 0hs₃:2 + 0 = xhc:2 2hd:1 2ht:{2, 1} Sht₁:{2, 1}.card = 2ht₂:¬0 = 2 ¬0 = 1ht₃:2 + 1 = xhst:{2, 0} {2, 1}Falsex:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:h:¬4 xha:2 2hb:0 2hs:{2, 0} Shs₁:{2, 0}.card = 2hs₂:¬0 = 2 ¬0 = 0hs₃:2 + 0 = xhc:2 2hd:2 2ht:{2, 2} Sht₁:{2, 2}.card = 2ht₂:¬0 = 2 ¬0 = 2ht₃:2 + 2 = xhst:{2, 0} {2, 2}Falsex:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:h:¬4 xha:2 2hb:1 2hs:{2, 1} Shs₁:{2, 1}.card = 2hs₂:¬0 = 2 ¬0 = 1hs₃:2 + 1 = xhc:0 2hd:0 2ht:{0, 0} Sht₁:{0, 0}.card = 2ht₂:¬0 = 0 ¬0 = 0ht₃:0 + 0 = xhst:{2, 1} {0, 0}Falsex:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:h:¬4 xha:2 2hb:1 2hs:{2, 1} Shs₁:{2, 1}.card = 2hs₂:¬0 = 2 ¬0 = 1hs₃:2 + 1 = xhc:0 2hd:1 2ht:{0, 1} Sht₁:{0, 1}.card = 2ht₂:¬0 = 0 ¬0 = 1ht₃:0 + 1 = xhst:{2, 1} {0, 1}Falsex:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:h:¬4 xha:2 2hb:1 2hs:{2, 1} Shs₁:{2, 1}.card = 2hs₂:¬0 = 2 ¬0 = 1hs₃:2 + 1 = xhc:0 2hd:2 2ht:{0, 2} Sht₁:{0, 2}.card = 2ht₂:¬0 = 0 ¬0 = 2ht₃:0 + 2 = xhst:{2, 1} {0, 2}Falsex:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:h:¬4 xha:2 2hb:1 2hs:{2, 1} Shs₁:{2, 1}.card = 2hs₂:¬0 = 2 ¬0 = 1hs₃:2 + 1 = xhc:1 2hd:0 2ht:{1, 0} Sht₁:{1, 0}.card = 2ht₂:¬0 = 1 ¬0 = 0ht₃:1 + 0 = xhst:{2, 1} {1, 0}Falsex:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:h:¬4 xha:2 2hb:1 2hs:{2, 1} Shs₁:{2, 1}.card = 2hs₂:¬0 = 2 ¬0 = 1hs₃:2 + 1 = xhc:1 2hd:1 2ht:{1, 1} Sht₁:{1, 1}.card = 2ht₂:¬0 = 1 ¬0 = 1ht₃:1 + 1 = xhst:{2, 1} {1, 1}Falsex:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:h:¬4 xha:2 2hb:1 2hs:{2, 1} Shs₁:{2, 1}.card = 2hs₂:¬0 = 2 ¬0 = 1hs₃:2 + 1 = xhc:1 2hd:2 2ht:{1, 2} Sht₁:{1, 2}.card = 2ht₂:¬0 = 1 ¬0 = 2ht₃:1 + 2 = xhst:{2, 1} {1, 2}Falsex:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:h:¬4 xha:2 2hb:1 2hs:{2, 1} Shs₁:{2, 1}.card = 2hs₂:¬0 = 2 ¬0 = 1hs₃:2 + 1 = xhc:2 2hd:0 2ht:{2, 0} Sht₁:{2, 0}.card = 2ht₂:¬0 = 2 ¬0 = 0ht₃:2 + 0 = xhst:{2, 1} {2, 0}Falsex:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:h:¬4 xha:2 2hb:1 2hs:{2, 1} Shs₁:{2, 1}.card = 2hs₂:¬0 = 2 ¬0 = 1hs₃:2 + 1 = xhc:2 2hd:1 2ht:{2, 1} Sht₁:{2, 1}.card = 2ht₂:¬0 = 2 ¬0 = 1ht₃:2 + 1 = xhst:{2, 1} {2, 1}Falsex:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:h:¬4 xha:2 2hb:1 2hs:{2, 1} Shs₁:{2, 1}.card = 2hs₂:¬0 = 2 ¬0 = 1hs₃:2 + 1 = xhc:2 2hd:2 2ht:{2, 2} Sht₁:{2, 2}.card = 2ht₂:¬0 = 2 ¬0 = 2ht₃:2 + 2 = xhst:{2, 1} {2, 2}Falsex:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:h:¬4 xha:2 2hb:2 2hs:{2, 2} Shs₁:{2, 2}.card = 2hs₂:¬0 = 2 ¬0 = 2hs₃:2 + 2 = xhc:0 2hd:0 2ht:{0, 0} Sht₁:{0, 0}.card = 2ht₂:¬0 = 0 ¬0 = 0ht₃:0 + 0 = xhst:{2, 2} {0, 0}Falsex:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:h:¬4 xha:2 2hb:2 2hs:{2, 2} Shs₁:{2, 2}.card = 2hs₂:¬0 = 2 ¬0 = 2hs₃:2 + 2 = xhc:0 2hd:1 2ht:{0, 1} Sht₁:{0, 1}.card = 2ht₂:¬0 = 0 ¬0 = 1ht₃:0 + 1 = xhst:{2, 2} {0, 1}Falsex:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:h:¬4 xha:2 2hb:2 2hs:{2, 2} Shs₁:{2, 2}.card = 2hs₂:¬0 = 2 ¬0 = 2hs₃:2 + 2 = xhc:0 2hd:2 2ht:{0, 2} Sht₁:{0, 2}.card = 2ht₂:¬0 = 0 ¬0 = 2ht₃:0 + 2 = xhst:{2, 2} {0, 2}Falsex:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:h:¬4 xha:2 2hb:2 2hs:{2, 2} Shs₁:{2, 2}.card = 2hs₂:¬0 = 2 ¬0 = 2hs₃:2 + 2 = xhc:1 2hd:0 2ht:{1, 0} Sht₁:{1, 0}.card = 2ht₂:¬0 = 1 ¬0 = 0ht₃:1 + 0 = xhst:{2, 2} {1, 0}Falsex:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:h:¬4 xha:2 2hb:2 2hs:{2, 2} Shs₁:{2, 2}.card = 2hs₂:¬0 = 2 ¬0 = 2hs₃:2 + 2 = xhc:1 2hd:1 2ht:{1, 1} Sht₁:{1, 1}.card = 2ht₂:¬0 = 1 ¬0 = 1ht₃:1 + 1 = xhst:{2, 2} {1, 1}Falsex:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:h:¬4 xha:2 2hb:2 2hs:{2, 2} Shs₁:{2, 2}.card = 2hs₂:¬0 = 2 ¬0 = 2hs₃:2 + 2 = xhc:1 2hd:2 2ht:{1, 2} Sht₁:{1, 2}.card = 2ht₂:¬0 = 1 ¬0 = 2ht₃:1 + 2 = xhst:{2, 2} {1, 2}Falsex:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:h:¬4 xha:2 2hb:2 2hs:{2, 2} Shs₁:{2, 2}.card = 2hs₂:¬0 = 2 ¬0 = 2hs₃:2 + 2 = xhc:2 2hd:0 2ht:{2, 0} Sht₁:{2, 0}.card = 2ht₂:¬0 = 2 ¬0 = 0ht₃:2 + 0 = xhst:{2, 2} {2, 0}Falsex:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:h:¬4 xha:2 2hb:2 2hs:{2, 2} Shs₁:{2, 2}.card = 2hs₂:¬0 = 2 ¬0 = 2hs₃:2 + 2 = xhc:2 2hd:1 2ht:{2, 1} Sht₁:{2, 1}.card = 2ht₂:¬0 = 2 ¬0 = 1ht₃:2 + 1 = xhst:{2, 2} {2, 1}Falsex:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:h:¬4 xha:2 2hb:2 2hs:{2, 2} Shs₁:{2, 2}.card = 2hs₂:¬0 = 2 ¬0 = 2hs₃:2 + 2 = xhc:2 2hd:2 2ht:{2, 2} Sht₁:{2, 2}.card = 2ht₂:¬0 = 2 ¬0 = 2ht₃:2 + 2 = xhst:{2, 2} {2, 2}False first | All goals completed! 🐙 | exact hst (x:S:Finset (Multiset )hS₁:2 S.cardhS₂: L S, L.card = 2 0 L (Multiset.map (fun x x ^ 1) L).sum = xa:b:c:d:h:¬4 xha:2 2hb:1 2hs:{2, 1} Shs₁:{2, 1}.card = 2hs₂:¬0 = 2 ¬0 = 1hs₃:2 + 1 = xhc:2 2hd:1 2ht:{2, 1} Sht₁:{2, 1}.card = 2ht₂:¬0 = 2 ¬0 = 1ht₃:2 + 1 = xhst:{2, 1} {2, 1}{2, 1} = {2, 1} All goals completed! 🐙)

Taxicab number for $k=5$, $m=2$, and $n=2$ is not known. Whether such a number exists is also not known.

@[category research open, AMS 11] theorem taxicab_for_5_2_2 : answer(sorry) x : , IsTaxicabFor 5 2 2 x := True x, IsTaxicabFor 5 2 2 x All goals completed! 🐙

Taxicab number for $k=5$ and $m=2$ is not-known for any $n ≥ 2$. Whether such a number exists is also not known.

@[category research open, AMS 11] theorem taxicab_for_5_2_n : answer(sorry) n : , n 2 ( x : , IsTaxicabFor 5 2 n x) := True n 2, x, IsTaxicabFor 5 2 n x All goals completed! 🐙end Taxicab