[Question]
  [
## Introduction
Consider a sequence of integers and one of its subsequences, say **A = [4 2 2 4 4 6 5]** and **B = [2 4 5]**.
We want to remove the elements of **B** from **A** in order, and there are several ways of doing that:
```
A = 4 2 2 4 4 6 5
B =   2   4     5
 -> 4   2   4 6
A = 4 2 2 4 4 6 5
B =     2 4     5
 -> 4 2     4 6
A = 4 2 2 4 4 6 5
B =   2     4   5
 -> 4   2 4   6
A = 4 2 2 4 4 6 5
B =     2   4   5
 -> 4 2   4   6
```
In all cases, the remaining sequence is the same, **[4 2 4 6]**.
If this happens, we say that **B** is *uniquely removable from* **A**.
## The task
Your inputs are two sequences of nonnegative integers, **A** and **B**, where **B** is guaranteed to be a subsequence of **A**.
The inputs may be equal, and they may be empty.
You can take them in any order you want, in any reasonable format.
Your output shall be a truthy value if **B** is uniquely removable from **A**, and a falsy value if not.
## Rules and scoring
You can write a full program or a function.
The lowest byte count wins.
## Test cases
```
[] [] -> True
[0,3] [] -> True
[1,0,1] [1] -> False
[0,2] [0,2] -> True
[2,2,1,1,2,2,2] [2,1] -> True
[4,2,2,4,4,6,5] [4,5] -> False
[10,5,10,10,5,10] [10,5,10] -> False
[4,2,2,4,4,6,5] [2,4,5] -> True
[1,1,1,0,0,0,1,1,1,0] [1,0,1,1] -> True
[0,1,0,0,0,0,1,1,0,1] [1,0,1,1] -> False
[0,4,0,0,4,1,4,2,2] [0,0,0,1,4] -> True
[0,2,2,25,0,2,2,26,0,0,2] [2,0,0,0,2] -> True
[1,1,1,3,2,1,3,2,2,3,3,2] [1,1,2,3,2] -> False
[0,3,2,0,1,3,2,0,0,0,3,2] [0,1,2,0,3] -> False
[5,7,2,7,7,1,7,7,5,2,7,7,5,2,2,7,5] [2,7,5,7,7,2] -> False
[5,4,0,5,4,5,4,1,0,4,2,1,1,2,4,4,0,2,2,1] [4,0,1,1,2,1] -> False
[0,1,4,0,1,4,0,1,5,1,4,4,2,0,0,1,1,1,2,4] [0,1,0,0,2,0,1,4] -> True
```
  
[Answer]
# Haskell, ~~90~~ 84 bytes
```
a%[]=[a]
(t:z)%x@(s:y)=[a|a<-z%y,t==s]++[t:s|s<-z%x]
_%_=[]
((all=<<(==).head).).(%)
```
Construct the list of all possible subtracted sequences nondeterministically and checks whether they are all equal.
Usage: 
```
*Main> mapM_(\(a,b)->let r=(((all=<<(==).head).).(%)) a b in putStrLn$concat[show a," ",show b," -> ",show r]) [([],[]), ([0,3],[]), ([1,0,1],[1]), ([0,2],[0,2]), ([2,2,1,1,2,2,2],[2,1]), ([4,2,2,4,4,6,5],[4,5]), ([10,5,10,10,5,10],[10,5,10]), ([4,2,2,4,4,6,5],[2,4,5]), ([1,1,1,0,0,0,1,1,1,0],[1,0,1,1]), ([0,1,0,0,0,0,1,1,0,1],[1,0,1,1]), ([0,4,0,0,4,1,4,2,2],[0,0,0,1,4]), ([0,2,2,25,0,2,2,26,0,0,2],[2,0,0,0,2]), ([1,1,1,3,2,1,3,2,2,3,3,2],[1,1,2,3,2]), ([0,3,2,0,1,3,2,0,0,0,3,2],[0,1,2,0,3]), ([5,7,2,7,7,1,7,7,5,2,7,7,5,2,2,7,5],[2,7,5,7,7,2]), ([5,4,0,5,4,5,4,1,0,4,2,1,1,2,4,4,0,2,2,1],[4,0,1,1,2,1]), ([0,1,4,0,1,4,0,1,5,1,4,4,2,0,0,1,1,1,2,4],[0,1,0,0,2,0,1,4])]
[] [] -> True
[0,3] [] -> True
[1,0,1] [1] -> False
[0,2] [0,2] -> True
[2,2,1,1,2,2,2] [2,1] -> True
[4,2,2,4,4,6,5] [4,5] -> False
[10,5,10,10,5,10] [10,5,10] -> False
[4,2,2,4,4,6,5] [2,4,5] -> True
[1,1,1,0,0,0,1,1,1,0] [1,0,1,1] -> True
[0,1,0,0,0,0,1,1,0,1] [1,0,1,1] -> False
[0,4,0,0,4,1,4,2,2] [0,0,0,1,4] -> True
[0,2,2,25,0,2,2,26,0,0,2] [2,0,0,0,2] -> True
[1,1,1,3,2,1,3,2,2,3,3,2] [1,1,2,3,2] -> False
[0,3,2,0,1,3,2,0,0,0,3,2] [0,1,2,0,3] -> False
[5,7,2,7,7,1,7,7,5,2,7,7,5,2,2,7,5] [2,7,5,7,7,2] -> False
[5,4,0,5,4,5,4,1,0,4,2,1,1,2,4,4,0,2,2,1] [4,0,1,1,2,1] -> False
[0,1,4,0,1,4,0,1,5,1,4,4,2,0,0,1,1,1,2,4] [0,1,0,0,2,0,1,4] -> True
```
Thanks to @Zgarb for saving 6 bytes!
[Answer]
# JavaScript (ES6), 141 ~~152 156 159~~
Recursive function - quite long
```
f=(a,b,i=0,j=0,r=a,S=new Set)=>(1/b[j]?1/a[i]&&f(a,b,i+1,j,r,S,a[i]-b[j]||f(a,b,i+1,j+1,r=[...r],r[i]=S)):S.add(0+r.filter(x=>1/x)),S.size<2)
```
*Less golfed*
```
f=(a, b, 
   i = 0, // current position to match in a
   j = 0, // current position to match in b
   r = a, // current result so far, A with elements of B removed - start == A
   S = new Set // set of possible "A removed B"
) => (
    1 / b[j] // check if j is still inside B
    ? 1 / a[i] // if i is inside A
      && (
        // in any case try to find current element of B in the remaining part of A
        f(a, b, i+1, j, r, S),
        a[i] == b[j] // if match was found between A and B
        && 
          // mark current element in a copy of r and 
          // look for the next element of B in the remaining part of A
          f(a, b, i+1, j+1, r=[...r], r[i]=S),
      )
    // else - j is not inside B, we have a solution in r
    // use filter to get a copy without the marked elements
    //  (note: 1/any_number == number_not_0, 1/Object == NaN)
    // then convert to string, to use as a key in S
    : S.add(0+a.filter(x=>1/x)),
    S.size<2 // return true if S has only 1 element
)  
```
**Test**
```
f=(a,b,i=0,j=0,r=a,S=new Set)=>(1/b[j]?1/a[i]&&f(a,b,i+1,j,r,S,a[i]-b[j]||f(a,b,i+1,j+1,r=[...r],r[i]=S)):S.add(0+r.filter(x=>1/x)),S.size<2)
out=(...x)=>O.textContent+=x.join` `+'\n'
;`[] [] -> True
[0,3] [] -> True
[1,0,1] [1] -> False
[0,2] [0,2] -> True
[2,2,1,1,2,2,2] [2,1] -> True
[4,2,2,4,4,6,5] [4,5] -> False
[10,5,10,10,5,10] [10,5,10] -> False
[4,2,2,4,4,6,5] [2,4,5] -> True
[1,1,1,0,0,0,1,1,1,0] [1,0,1,1] -> True
[0,1,0,0,0,0,1,1,0,1] [1,0,1,1] -> False
[0,4,0,0,4,1,4,2,2] [0,0,0,1,4] -> True
[0,2,2,25,0,2,2,26,0,0,2] [2,0,0,0,2] -> True
[1,1,1,3,2,1,3,2,2,3,3,2] [1,1,2,3,2] -> False
[0,3,2,0,1,3,2,0,0,0,3,2] [0,1,2,0,3] -> False
[5,7,2,7,7,1,7,7,5,2,7,7,5,2,2,7,5] [2,7,5,7,7,2] -> False
[5,4,0,5,4,5,4,1,0,4,2,1,1,2,4,4,0,2,2,1] [4,0,1,1,2,1] -> False
[0,1,4,0,1,4,0,1,5,1,4,4,2,0,0,1,1,1,2,4] [0,1,0,0,2,0,1,4] -> True`
.split('\n').forEach(t=>{
  var [a,b,_,k]=t.match(/\S+/g)
  var r=f(eval(a),eval(b))
  out(r==(k[0]=='T')?'OK':'KO',a,b,r,k)
})
```
```
<pre id=O></pre>
```
[Answer]
# Pyth - 27 bytes
On mobile in school right now, so not fully golfed.
```
JE!t{.DLQfqJ@LQT{I#{SM^UQlJ
```
[Test Suite](http://pyth.herokuapp.com/?code=JE%21t%7B.DLQfqJ%40LQT%7BI%23%7BSM%5EUQlJ&test_suite=1&test_suite_input=%5B%5D%0A%5B%5D%0A%5B0%2C+3%5D%0A%5B%5D%0A%5B1%2C0%2C1%5D%0A%5B1%5D%0A%5B4%2C2%2C2%2C4%2C4%2C6%2C5%5D%0A%5B2%2C4%2C5%5D%0A%5B4%2C2%2C2%2C4%2C4%2C6%2C5%5D%0A%5B4%2C5%5D&debug=0&input_size=2)
[Answer]
## JavaScript (ES6), ~~116~~ ~~114~~ 113 bytes
Returns `false` or `true`.
```
(a,b,p)=>((F=(a,i,m)=>1/b[i]?a.map((n,j)=>m>j|n-b[i]||F(a.filter((_,k)=>j-k),i+1,j)):p?r|=p!=a:p=a+'')(a,r=0),!r)
```
### Formatted and commented
```
(                                     // given:
  a, b,                               // - a, b = input arrays
  p                                   // - p = reference pattern, initially undefined
) => (                                //
  (F = (                              // F is our recursive search function, with:
    a,                                // - a = current working copy of the main array
    i,                                // - i = index in 'b'
    m                                 // - m = minimum index of matching values in 'a'
  ) =>                                //
    1 / b[i] ?                        // if we haven't reached the end of 'b':
      a.map((n, j) =>                 //   for each element 'n' at index 'j' in 'a':
        m > j | n - b[i] ||           //     if 'n' is a valid matching value,
        F(                            //     do a recursive call to F(), using:
          a.filter((_, k) => j - k),  //     - a copy of 'a' without the current element
          i + 1,                      //     - the next index in 'b'
          j                           //     - 'j' as the new minimum index in 'a'
        )                             //
      )                               //
    :                                 // else:
      p ?                             //   if the reference pattern is already set:
        r |= p != a                   //     check if it's matching the current 'a'
      :                               //   else:
        p = a + ''                    //     set the current 'a' as the reference pattern
  )(a, r = 0),                        //  initial call to F() + initialization of 'r'
  !r                                  //  yields the final result
)                                     //
```
### Test cases
```
let f =
(a,b,p)=>((F=(a,i,m)=>1/b[i]?a.map((n,j)=>m>j|n-b[i]||F(a.filter((_,k)=>j-k),i+1,j)):p?r|=p!=a:p=a+'')(a,r=0),!r)
console.log(f([],[]));                                                        // -> true
console.log(f([0,3],[]));                                                     // -> true
console.log(f([1,0,1],[1]));                                                  // -> false
console.log(f([0,2],[0,2]));                                                  // -> true
console.log(f([2,2,1,1,2,2,2],[2,1]));                                        // -> true
console.log(f([4,2,2,4,4,6,5],[4,5]));                                        // -> false
console.log(f([10,5,10,10,5,10],[10,5,10]));                                  // -> false
console.log(f([4,2,2,4,4,6,5],[2,4,5]));                                      // -> true
console.log(f([1,1,1,0,0,0,1,1,1,0],[1,0,1,1]));                              // -> true
console.log(f([0,1,0,0,0,0,1,1,0,1],[1,0,1,1]));                              // -> false
console.log(f([0,4,0,0,4,1,4,2,2],[0,0,0,1,4]));                              // -> true
console.log(f([0,2,2,25,0,2,2,26,0,0,2],[2,0,0,0,2]));                        // -> true
console.log(f([1,1,1,3,2,1,3,2,2,3,3,2],[1,1,2,3,2]));                        // -> false
console.log(f([0,3,2,0,1,3,2,0,0,0,3,2],[0,1,2,0,3]));                        // -> false
console.log(f([5,7,2,7,7,1,7,7,5,2,7,7,5,2,2,7,5],[2,7,5,7,7,2]));            // -> false
console.log(f([5,4,0,5,4,5,4,1,0,4,2,1,1,2,4,4,0,2,2,1],[4,0,1,1,2,1]));      // -> false
console.log(f([0,1,4,0,1,4,0,1,5,1,4,4,2,0,0,1,1,1,2,4],[0,1,0,0,2,0,1,4]));  // -> true
```
[Answer]
# [MATL](http://github.com/lmendo/MATL), 27 bytes
```
n:inXN!"1G@&)w2G=?}x]]tvdz~
```
The longest test cases run out of time in the online compiler.
[Try it online!](http://matl.tryitonline.net/#code=bjppblhOISIxR0AmKXcyRz0_fXhdXXR2ZHp-&input=WzQsMiwyLDQsNCw2LDVdClsyLDQsNV0)
[Answer]
# JavaScript (Firefox 30+), ~~159~~ 147 bytes
```
f=(a,b,i=f(a,b,0))=>i?i.every(x=>x+""==i[0]):b+b?a+a&&[for(n of a)if(a[i++]==b[0])for(x of f(a.slice(i),b.slice(1),0))[...a.slice(0,i-1),...x]]:[a]
```
Here's a couple of alternate approaches, both anonymous functions:
```
(a,b,f=(a,b,i=0)=>b+b?a+a&&[for(n of a)if(a[i++]==b[0])for(x of f(a.slice(i),b.slice(1)))[...a.slice(0,i-1),...x]]:[a],c=f(a,b))=>c.every(x=>x+""==c[0])
(a,b,f=(a,b,i=0)=>b+b?a+a&&[for(n of a)if(a[i++]==b[0])for(x of f(a.slice(i),b.slice(1)))[...a.slice(0,i-1),...x]]:[a])=>new Set(f(a,b).map(btoa)).size<2
```
### Test snippet
```
f=(a,b,i=f(a,b,0))=>i?i.every(x=>x+""==i[0]):b+b?a+a&&[for(n of a)if(a[i++]==b[0])for(x of f(a.slice(i),b.slice(1),0))[...a.slice(0,i-1),...x]]:[a]
T.textContent = T.textContent.split`
`.map(x => x + ` (${f(...x.split` `.slice(0,2).map(eval))})`).join`
`
```
```
<pre id=T>[] [] -> True
[0,3] [] -> True
[1,0,1] [1] -> False
[0,2] [0,2] -> True
[2,2,1,1,2,2,2] [2,1] -> True
[4,2,2,4,4,6,5] [4,5] -> False
[10,5,10,10,5,10] [10,5,10] -> False
[4,2,2,4,4,6,5] [2,4,5] -> True
[1,1,1,0,0,0,1,1,1,0] [1,0,1,1] -> True
[0,1,0,0,0,0,1,1,0,1] [1,0,1,1] -> False
[0,4,0,0,4,1,4,2,2] [0,0,0,1,4] -> True
[0,2,2,25,0,2,2,26,0,0,2] [2,0,0,0,2] -> True
[1,1,1,3,2,1,3,2,2,3,3,2] [1,1,2,3,2] -> False
[0,3,2,0,1,3,2,0,0,0,3,2] [0,1,2,0,3] -> False
[5,7,2,7,7,1,7,7,5,2,7,7,5,2,2,7,5] [2,7,5,7,7,2] -> False
[5,4,0,5,4,5,4,1,0,4,2,1,1,2,4,4,0,2,2,1] [4,0,1,1,2,1] -> False
[0,1,4,0,1,4,0,1,5,1,4,4,2,0,0,1,1,1,2,4] [0,1,0,0,2,0,1,4] -> True</pre>
```
[Answer]
# Mathematica, 128 bytes
```
h=Length;n=ToExpression;g=ToString;y=Array;h@Union@ReplaceList[#2,n@Riffle[y["a"<>g@#<>"___"&,t=h@#+1],#]->n@y["a"<>g@#&,t]]==1&
```
Unnamed function taking two list arguments, where the first is the subsequence and the second is the full sequence; outputs `True` or `False`.
The core part is the following sequence, ungolfed for readability:
```
ReplaceList[#2, ToExpression @
  Riffle[
    Array["a" <> ToString@# <> "___" &, Length@# + 1]
    , #
  ] -> ToExpression @ 
    Array["a" <> ToString@#& , Length@# + 1 ]
]
```
Here `#` represents the subsequence—for example, `{2,4,5}`. The first `Array` command creates a list of strings like `{"a1___","a2___","a3___","a4___"}`, which is then `Riffle`d together with `#` to yield a weird list like `{"a1___",2,"a2___",4,"a3___",5,"a4___"}`; then this list is cast into an actual Mathematica expression. For the example `{2,4,5}`, a partial evaluation of this core code is
```
ReplaceList[#2, {a1___,2,a2___,4,a3___,5,a4___} -> {a1,a2,a3,a4}]
```
which exactly gives a list of all possible ways to remove the subsequence `{2,4,5}` from `#2` and leave the rest of the list alone.
After this list is generated, we simply remove duplicates using `Union` and test whether the length of the resulting output is 1 or not.
]