/// <summary>
/// Coerces an integer into a natural.
/// </summary>
public Z3Expr MkNegCoercion(Z3IntExpr i)
{
var zero = Context.MkInt(0);
var one = Context.MkInt(1);
var two = Context.MkInt(2);
var oddCase = BoxingFun.Apply(i.Add(Context, one).Div(Context, two));
var coercion = i.IsEven(Context).Ite(
Context,
BoxingFun.Apply(i.Neg(Context).Div(Context, two)),
oddCase);
return(coercion);
}
/// <summary>
/// Coerces an integer into a pos integer.
/// </summary>
public Z3Expr MkPosCoercion(Z3IntExpr i)
{
var zero = Context.MkInt(0);
var one = Context.MkInt(1);
var two = Context.MkInt(2);
var oddCase = BoxingFun.Apply(one.Sub(Context, i).Div(Context, two));
var coercion = i.IsEven(Context).Ite(
Context,
BoxingFun.Apply(i.Div(Context, two)),
oddCase);
coercion = i.Eq(Context, one).Ite(
Context,
BoxingFun.Apply(zero),
coercion);
return(coercion);
}
/// <summary>
/// Coerces an integer into a natural.
/// </summary>
public Z3Expr MkNatCoercion(Z3IntExpr i)
{
var zero = Context.MkInt(0);
var one = Context.MkInt(1);
var two = Context.MkInt(2);
var evenCase = BoxingFun.Apply(i.Neg(Context).Div(Context, two));
var coercion = i.IsEven(Context).Not(Context).Ite(
Context,
BoxingFun.Apply(i.Add(Context, one).Div(Context, two)),
evenCase);
coercion = i.Eq(Context, zero).Ite(
Context,
BoxingFun.Apply(zero),
coercion);
return(coercion);
}