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! FORTRAN QUANTUM INTERFACE MODULE
! Supercomputer ↔ Haskell/Quantum Bridge for Theorem 3 Offload
! =====================================================================
! Purpose:
! - Provides Fortran API for offloading Theorem 3 (genus-0 forcing) to
! Haskell kernel via C FFI
! - Marshals polynomial coefficients from Fortran to C string
! - Handles energy budget accounting
! - Returns genus proof status (0=success, 1=blocked, 2=counterexample)
!
! Usage:
! use quantum_theorem3
! call offload_theorem3_to_quantum(poly_str, energy_budget, status, genus)
!
! Standard: Fortran 2018, C Interop
! Compiler: GNU Fortran (gfortran)
! =====================================================================
module quantum_theorem3
use iso_c_binding
use bob_kinds, only: i4, dp
implicit none
private
! Public interface
public :: offload_theorem3_to_quantum
public :: polynomial_to_string
public :: THEOREM3_SUCCESS
public :: THEOREM3_BLOCKED
public :: THEOREM3_COUNTEREXAMPLE
public :: THEOREM3_PARSE_ERROR
public :: THEOREM3_QUANTUM_FAILED
! Status codes (must match Haskell return values)
integer, parameter :: THEOREM3_SUCCESS = 0 ! Genus-0 proved + quantum verified
integer, parameter :: THEOREM3_BLOCKED = 1 ! Obstruction hit (singular point, etc.)
integer, parameter :: THEOREM3_COUNTEREXAMPLE = 2 ! Higher genus detected
integer, parameter :: THEOREM3_PARSE_ERROR = 3 ! Polynomial string parse failed
integer, parameter :: THEOREM3_QUANTUM_FAILED = 4 ! Quantum verification rejected
! ===================================================================
! C INTERFACE TO HASKELL FFI
! ===================================================================
interface
function haskell_theorem3_offload(poly_str, energy_budget) bind(C, name="haskell_theorem3_offload")
use iso_c_binding
implicit none
character(kind=c_char), intent(in) :: poly_str(*)
integer(c_int), value :: energy_budget
integer(c_int) :: haskell_theorem3_offload
end function haskell_theorem3_offload
end interface
contains
! ===================================================================
! MAIN PUBLIC SUBROUTINE: Offload Theorem 3 to Quantum Chip
! ===================================================================
subroutine offload_theorem3_to_quantum(poly_str, energy_budget, result_status, result_genus)
! ================================================================
! Arguments:
! poly_str (in) : Polynomial string "1*u^2 + 2*u*x + 3*x^2"
! energy_budget (in) : Energy budget (integer)
! result_status (out): Status code (0,1,2,3,4)
! result_genus (out) : Genus bound (0 if success, >0 if counterex)
! ================================================================
character(len=*), intent(in) :: poly_str
integer(i4), intent(in) :: energy_budget
integer(i4), intent(out) :: result_status
integer(i4), intent(out) :: result_genus
integer(c_int) :: haskell_result
character(kind=c_char, len=:), allocatable :: c_poly_str
integer(c_int) :: c_budget
! Convert Fortran string to C string (null-terminated)
allocate(character(kind=c_char, len=len_trim(poly_str)+1) :: c_poly_str)
c_poly_str = trim(poly_str) // c_null_char
! Convert energy budget to C int
c_budget = int(energy_budget, c_int)
! Call Haskell bridge
haskell_result = haskell_theorem3_offload(c_poly_str, c_budget)
! Marshal result back to Fortran
result_status = int(haskell_result, i4)
! Extract genus from status code
! In this simplified API:
! 0 = success, genus = 0 (rational curve)
! 1 = blocked, genus = -1 (unknown)
! 2 = counterexample, genus = unknown (reported separately from kernel)
! 3 = parse error, genus = -1
! 4 = quantum failed, genus = -1
select case (result_status)
case (THEOREM3_SUCCESS)
result_genus = 0 ! Genus-0 proved
case (THEOREM3_BLOCKED)
result_genus = -1 ! Unknown (obstruction)
case (THEOREM3_COUNTEREXAMPLE)
result_genus = 1 ! At least genus > 0
case default
result_genus = -1 ! Error
end select
! Cleanup
deallocate(c_poly_str)
end subroutine offload_theorem3_to_quantum
! ===================================================================
! HELPER: Convert Polynomial Coefficients to String
! ===================================================================
function polynomial_to_string(coeffs, degrees_u, degrees_x) result(poly_str)
! ================================================================
! Purpose: Build polynomial string from Fortran arrays
! Input arrays must be same length
! Example: coeffs=[1,2,3], degrees_u=[2,1,0], degrees_x=[0,1,2]
! → "1*u^2 + 2*u^1*x^1 + 3*x^2"
! ================================================================
real(dp), intent(in) :: coeffs(:)
integer(i4), intent(in) :: degrees_u(:)
integer(i4), intent(in) :: degrees_x(:)
character(len=:), allocatable :: poly_str
integer :: i, n, str_len
character(len=4096) :: buffer
character(len=256) :: term_str
n = size(coeffs)
if (n == 0) then
poly_str = "0"
return
end if
! Build polynomial string
buffer = ""
do i = 1, n
! Format coefficient
if (i == 1) then
! First term: no leading + sign
write(term_str, '(F0.1, A, I0, A, I0)') &
coeffs(i), "*u^", degrees_u(i), "*x^", degrees_x(i)
else
! Subsequent terms: add + sign (or - for negative coeffs)
if (coeffs(i) >= 0.0_dp) then
write(term_str, '(A, F0.1, A, I0, A, I0)') &
" + ", coeffs(i), "*u^", degrees_u(i), "*x^", degrees_x(i)
else
write(term_str, '(A, F0.1, A, I0, A, I0)') &
" ", coeffs(i), "*u^", degrees_u(i), "*x^", degrees_x(i)
end if
end if
! Append to buffer
str_len = len_trim(buffer)
buffer = buffer(1:str_len) // trim(adjustl(term_str))
end do
! Return trimmed result
poly_str = trim(buffer)
end function polynomial_to_string
! ===================================================================
! HELPER: Parse Genus Bound from Genus Code
! ===================================================================
function extract_genus_from_result(status_code) result(genus)
integer(i4), intent(in) :: status_code
integer(i4) :: genus
select case (status_code)
case (THEOREM3_SUCCESS)
genus = 0
case (THEOREM3_COUNTEREXAMPLE)
genus = 1 ! At least 1 (higher genus detected)
case default
genus = -1 ! Unknown/error
end select
end function extract_genus_from_result
end module quantum_theorem3
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