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Added a simplify pattern for XOR that reduces A xor 0 to A. #498

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Added a simplify pattern for XOR that reduces A xor 0 to A. #498

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1b3909d
Added a simplify pattern for XOR that reduces A xor 0 to A.
jclapis Aug 23, 2021
9e4b6b8
Added boolean logic patterns and tests for XOR (including negation)
jclapis Aug 23, 2021
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10 changes: 10 additions & 0 deletions Sources/AngouriMath/Functions/Simplification/Patterns/Patterns.Common.cs
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Expand Up @@ -227,6 +227,16 @@ internal static partial class Patterns
Mulf(Rational(var mOne, var den), var any1) when mOne == -1 && den != 1 => -(any1 / den),
Mulf(var any1, Rational(var mOne, var den)) when mOne == -1 && den != 1 => -(any1 / den),

// a xor false = a
Xorf(var any1, Entity.Boolean any2) when any2 == false => any1,
Xorf(var any2, var any1) when any2 == false => any1,
Xorf(var any1, Integer any2) when any2 == 0 => any1,
Xorf(Integer any2, var any1) when any2 == 0 => any1,
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There's no logic backing xor on numbers, so this pattern is not particularly useful. Or you have some other, broader idea regarding xor? Please, share!

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I'm not sure what you mean about backing logic; are you referring to the solver system? If so, we're just using the symbolic algebra representation and simplification systems so this isn't something we had considered. In quantum notation, you see things like this quite frequently:

image

That is, some variable XOR'd against some other variable. In some cases one of those variables is simply the integer 0, and that can be simplified to just using the other value. That's the use case this was intended to support.

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@WhiteBlackGoose WhiteBlackGoose Aug 24, 2021 •
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Right. What I am saying is that we don't support boolean operators on integers. So if we want to add it, it should be added for all boolean operators and for all cases, not only for a few cases for xor. That's what I mean 😅 . But before doing so, we need to think how it will be designed.

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By the way, maybe you want to join our discord server (see the repo's readme's green badge)? It's a chat, so we can discuss it more conveniently there (and having others potentially involved)

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Sure, I'll hop in tomorrow if you believe there's more to this discussion that what you've mentioned here.


// a xor true = not a
Xorf(var any1, var any2) when any2 == true => new Notf(any1),
Xorf(var any2, var any1) when any2 == true => new Notf(any1),
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You can write it as Xorf(var any1, Boolean(true)) => any1.Not() thanks to pattern matching. But don't those rules in fact already exist? Let me check


_ => x
};
}
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6 changes: 6 additions & 0 deletions Sources/Tests/UnitTests/PatternsTest/SimplifyTest.cs
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Expand Up @@ -95,6 +95,12 @@ [Fact] public void Patt2() => AssertSimplify(
// TODO: Smart factorizer
[Fact] public void Divide2() => AssertSimplifyToString("(x3 + 3 x 2 y + 3 x y 2 + y3) / (x + y)", "x ^ 2 + 2 * x * y + y ^ 2");
[Fact] public void Divide3() => AssertSimplifyToString("(x2 + 2 x y + y2 + 1) / (x + y)", "x + 1 / (x + y) + y");
[Fact] public void Xor1() => AssertSimplify(new Entity.Xorf(x, 0), x);
[Fact] public void Xor2() => AssertSimplify(new Entity.Xorf(0, x), x);
[Fact] public void Xor3() => AssertSimplify(new Entity.Xorf(false, x), x);
[Fact] public void Xor4() => AssertSimplify(new Entity.Xorf(x, false), x);
[Fact] public void Xor5() => AssertSimplify(new Entity.Xorf(x, true), new Entity.Notf(x));
[Fact] public void Xor6() => AssertSimplify(new Entity.Xorf(true, x), new Entity.Notf(x));

[Fact] public void BigSimple1() => AssertSimplifyToString(
"1+2x*-1+2x*2+x^2+2x+2x*-4+2x*4+2x*2x*-1+2x*2x*2+2x*x^2+x^2+x^2*-4+x^2*4+x^2*2*x*-1+x^2*2x*2+x^2*x^2",
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