more tactic descriptions

src/tactic/ufbv/macro_finder_tactic.h

@@ -13,7 +13,45 @@ Author:
 
     Christoph (cwinter) 2012-10-26
 
-Notes:
+Tactic Description
+
+## Tactic macro-finder
+
+### Short Description 
+
+Identifies and applies macros.
+
+### Long Description
+
+It finds implicit macro definitions in quantifiers. 
+A main instance of a macro an equality that defines a function `f` using some term `t` that does not contain `f`.
+Other instances of macros are also recognized by the macro finder.
+
+* `(forall (x) (= (f x) t))`
+
+* `not (= (p x) t)` is recognized as `(p x) = (not t)`
+
+* `(iff (= (f x) t) cond)`  rewrites to `(f x) = (if cond t else (k x))`
+   * add clause `(not (= (k x) t))`
+
+* `(= (+ (f x) s) t)` becomes `(= (f x) (- t s))`
+
+* `(= (+ (* -1 (f x)) x) t)`  becomes `(= (f x) (- (- t s)))`
+
+### Example
+
+```z3
+(declare-fun f (Int) Int)
+(declare-fun p (Int) Bool)
+
+(assert (forall ((x Int)) (= (+ (f x) x) 3)))
+(assert (p (f 8)))
+(apply macro-finder)
+```
+
+### Notes
+
+* Supports proofs, unsat cores, but not goals with recursive function definitions.
 
 --*/
 #pragma once