Create a running theory with Peano axioms

src/main/scala/lisa/proven/mathematics/Peano.scala

+package lisa.proven.mathematics
+
+import lisa.utils.Helpers.{given, *}
+import lisa.kernel.fol.FOL.*
+import lisa.kernel.proof.RunningTheory
+
+object Peano {
+  type Axiom = Formula
+  final val (x, y) =
+    (VariableLabel("x"), VariableLabel("y"))
+
+  final val zero: Term = ConstantFunctionLabel("0", 0)()
+  final val s = ConstantFunctionLabel("S", 1)
+  final val plus = ConstantFunctionLabel("+", 2)
+  final val times = ConstantFunctionLabel("*", 2)
+  final val sPhi: SchematicPredicateLabel = SchematicPredicateLabel("?p", 1)
+
+  final val ax1ZeroSuccessor: Axiom = forall(x, !(s(x) === zero))
+  final val ax2Injectivity: Axiom = forall(x, forall(y, (s(x) === s(y)) ==> (x === y)))
+  final val ax3neutral: Axiom = forall(x, plus(x, zero) === x)
+  final val ax4plus: Axiom = forall(x, forall(y, plus(x, s(y)) === s(plus(x, y))))
+  final val ax5: Axiom = forall(x, times(x, zero) === zero)
+  final val ax6: Axiom = forall(x, forall(y, times(x, s(y)) === plus(times(x, y), x)))
+  final val ax7induction: Axiom = (sPhi(zero) /\ forall(x, sPhi(x) ==> sPhi(s(x)))) ==> forall(x, sPhi(x))
+
+  final val runningPeanoTheory: RunningTheory = new RunningTheory()
+  final val functions: Set[ConstantFunctionLabel] = Set(ConstantFunctionLabel("0", 0), s, plus, times)
+  functions.foreach(runningPeanoTheory.addSymbol(_))
+
+  private val peanoAxioms: Set[(String, Axiom)] = Set(
+    ("A1", ax1ZeroSuccessor),
+    ("A2", ax2Injectivity),
+    ("A3", ax3neutral),
+    ("A4", ax4plus),
+    ("A5", ax5),
+    ("A6", ax6),
+    ("Induction", ax7induction)
+  )
+  peanoAxioms.foreach(a => runningPeanoTheory.addAxiom(a._1, a._2))
+}