Documentation

Mathlib.Tactic.Ring.RingNF

ring_nf tactic #

A tactic which uses ring to rewrite expressions. This can be used non-terminally to normalize ring expressions in the goal such as ⊢ P (x + x + x) ~> ⊢ P (x * 3), as well as being able to prove some equations that ring cannot because they involve ring reasoning inside a subterm, such as sin (x + y) + sin (y + x) = 2 * sin (x + y).

The normalization style for ring_nf.

  • SOP : RingMode

    Sum-of-products form, like x + x * y * 2 + z ^ 2.

  • raw : RingMode

    Raw form: the representation ring uses internally.

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      Configuration for ring_nf.

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            Function elaborating RingNF.Config.

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              Evaluates an expression e into a normalized representation as a polynomial.

              This is a variant of Mathlib.Tactic.Ring.eval, the main driver of the ring tactic. It differs in

              • operating on Expr (input) and Simp.Result (output), rather than typed Qq versions of these;
              • throwing an error if the expression e is an atom for the ring tactic.
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                theorem Mathlib.Tactic.RingNF.add_assoc_rev {R : Type u_1} [CommSemiring R] (a b c : R) :
                a + (b + c) = a + b + c
                theorem Mathlib.Tactic.RingNF.mul_assoc_rev {R : Type u_1} [CommSemiring R] (a b c : R) :
                a * (b * c) = a * b * c
                theorem Mathlib.Tactic.RingNF.mul_neg {R : Type u_2} [Ring R] (a b : R) :
                a * -b = -(a * b)
                theorem Mathlib.Tactic.RingNF.add_neg {R : Type u_2} [Ring R] (a b : R) :
                a + -b = a - b

                A cleanup routine, which simplifies normalized polynomials to a more human-friendly format.

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                  ring_nf simplifies expressions in the language of commutative (semi)rings, which rewrites all ring expressions into a normal form, allowing variables in the exponents.

                  ring_nf works as both a tactic and a conv tactic.

                  See also the ring tactic for solving a goal which is an equation in the language of commutative (semi)rings.

                  • ring_nf! will use a more aggressive reducibility setting to identify atoms.
                  • ring_nf (config := cfg) allows for additional configuration (see RingNF.Config):
                    • red: the reducibility setting (overridden by !)
                    • zetaDelta: if true, local let variables can be unfolded (overridden by !)
                    • recursive: if true, ring_nf will also recurse into atoms
                  • ring_nf at l1 l2 ... can be used to rewrite at the given locations.

                  Examples: This can be used non-terminally to normalize ring expressions in the goal such as ⊢ P (x + x + x) ~> ⊢ P (x * 3), as well as being able to prove some equations that ring cannot because they involve ring reasoning inside a subterm, such as sin (x + y) + sin (y + x) = 2 * sin (x + y).

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                    ring_nf simplifies expressions in the language of commutative (semi)rings, which rewrites all ring expressions into a normal form, allowing variables in the exponents.

                    ring_nf works as both a tactic and a conv tactic.

                    See also the ring tactic for solving a goal which is an equation in the language of commutative (semi)rings.

                    • ring_nf! will use a more aggressive reducibility setting to identify atoms.
                    • ring_nf (config := cfg) allows for additional configuration (see RingNF.Config):
                      • red: the reducibility setting (overridden by !)
                      • zetaDelta: if true, local let variables can be unfolded (overridden by !)
                      • recursive: if true, ring_nf will also recurse into atoms
                    • ring_nf at l1 l2 ... can be used to rewrite at the given locations.

                    Examples: This can be used non-terminally to normalize ring expressions in the goal such as ⊢ P (x + x + x) ~> ⊢ P (x * 3), as well as being able to prove some equations that ring cannot because they involve ring reasoning inside a subterm, such as sin (x + y) + sin (y + x) = 2 * sin (x + y).

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                      ring_nf simplifies expressions in the language of commutative (semi)rings, which rewrites all ring expressions into a normal form, allowing variables in the exponents.

                      ring_nf works as both a tactic and a conv tactic.

                      See also the ring tactic for solving a goal which is an equation in the language of commutative (semi)rings.

                      • ring_nf! will use a more aggressive reducibility setting to identify atoms.
                      • ring_nf (config := cfg) allows for additional configuration (see RingNF.Config):
                        • red: the reducibility setting (overridden by !)
                        • zetaDelta: if true, local let variables can be unfolded (overridden by !)
                        • recursive: if true, ring_nf will also recurse into atoms
                      • ring_nf at l1 l2 ... can be used to rewrite at the given locations.

                      Examples: This can be used non-terminally to normalize ring expressions in the goal such as ⊢ P (x + x + x) ~> ⊢ P (x * 3), as well as being able to prove some equations that ring cannot because they involve ring reasoning inside a subterm, such as sin (x + y) + sin (y + x) = 2 * sin (x + y).

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                        ring1 solves the goal when it is an equality in commutative (semi)rings, allowing variables in the exponent.

                        This version of ring fails if the target is not an equality.

                        • ring1! uses a more aggressive reducibility setting to determine equality of atoms.

                        Extensions:

                          • ring1_nf additionally uses ring_nf to simplify in atoms.
                          • ring1_nf! will use a more aggressive reducibility setting to determine equality of atoms.
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                          ring1 solves the goal when it is an equality in commutative (semi)rings, allowing variables in the exponent.

                          This version of ring fails if the target is not an equality.

                          • ring1! uses a more aggressive reducibility setting to determine equality of atoms.

                          Extensions:

                            • ring1_nf additionally uses ring_nf to simplify in atoms.
                            • ring1_nf! will use a more aggressive reducibility setting to determine equality of atoms.
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                            Elaborator for the ring_nf tactic.

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                              ring_nf simplifies expressions in the language of commutative (semi)rings, which rewrites all ring expressions into a normal form, allowing variables in the exponents.

                              ring_nf works as both a tactic and a conv tactic.

                              See also the ring tactic for solving a goal which is an equation in the language of commutative (semi)rings.

                              • ring_nf! will use a more aggressive reducibility setting to identify atoms.
                              • ring_nf (config := cfg) allows for additional configuration (see RingNF.Config):
                                • red: the reducibility setting (overridden by !)
                                • zetaDelta: if true, local let variables can be unfolded (overridden by !)
                                • recursive: if true, ring_nf will also recurse into atoms
                              • ring_nf at l1 l2 ... can be used to rewrite at the given locations.

                              Examples: This can be used non-terminally to normalize ring expressions in the goal such as ⊢ P (x + x + x) ~> ⊢ P (x * 3), as well as being able to prove some equations that ring cannot because they involve ring reasoning inside a subterm, such as sin (x + y) + sin (y + x) = 2 * sin (x + y).

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                                ring solves equations in commutative (semi)rings, allowing for variables in the exponent. If the goal is not appropriate for ring (e.g. not an equality) ring_nf will be suggested. See also ring1, which fails if the goal is not an equality.

                                • ring! will use a more aggressive reducibility setting to determine equality of atoms.

                                Examples:

                                example (n : ℕ) (m : ℤ) : 2^(n+1) * m = 2 * 2^n * m := by ring
                                example (a b : ℤ) (n : ℕ) : (a + b)^(n + 2) = (a^2 + b^2 + a * b + b * a) * (a + b)^n := by ring
                                example (x y : ℕ) : x + id y = y + id x := by ring!
                                example (x : ℕ) (h : x * 2 > 5): x + x > 5 := by ring; assumption -- suggests ring_nf
                                
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                                  ring solves equations in commutative (semi)rings, allowing for variables in the exponent. If the goal is not appropriate for ring (e.g. not an equality) ring_nf will be suggested. See also ring1, which fails if the goal is not an equality.

                                  • ring! will use a more aggressive reducibility setting to determine equality of atoms.

                                  Examples:

                                  example (n : ℕ) (m : ℤ) : 2^(n+1) * m = 2 * 2^n * m := by ring
                                  example (a b : ℤ) (n : ℕ) : (a + b)^(n + 2) = (a^2 + b^2 + a * b + b * a) * (a + b)^n := by ring
                                  example (x y : ℕ) : x + id y = y + id x := by ring!
                                  example (x : ℕ) (h : x * 2 > 5): x + x > 5 := by ring; assumption -- suggests ring_nf
                                  
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                                    The tactic ring evaluates expressions in commutative (semi)rings. This is the conv tactic version, which rewrites a target which is a ring equality to True.

                                    See also the ring tactic.

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                                      The tactic ring evaluates expressions in commutative (semi)rings. This is the conv tactic version, which rewrites a target which is a ring equality to True.

                                      See also the ring tactic.

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                                        We register ring with the hint tactic.