Long-lived software is a challenge. This was seen very clearly a couple of years ago in the “US COBOL crisis”, but the reasons are less clearly understood, and are worth exploring. The speaker works in Computer Algebra, where “younger” systems are 30-40 years old, and the algorithmic kernel of SageMath, the newest major system, is actually 55 years old, and the people who can debug it are in single figures. More recently, very substantial retooling was required to enable Line 14, the driverless line, of the Paris Métro to be extended. Having reviewed these cases, the speaker will make some tentative suggestions for the management of long-lived software.

1. Have we a Human Ecosystem?
James Davenport1
masjhd@bath.ac.uk
Departments of Computer Science and Mathematical Sciences
University of Bath
1
Many thanks to Capgemini staff and members of SC2
[ABB+
16],
H2020-FETOPEN-2015-CSA 712689
James Davenportmasjhd@bath.ac.uk Human Ecosystem? 1 / 17

2. COBOL
James Davenportmasjhd@bath.ac.uk Human Ecosystem? 2 / 17

3. Why am I talking about COBOL here?
James Davenportmasjhd@bath.ac.uk Human Ecosystem? 3 / 17

4. Why am I talking about COBOL here?
Because in 2020 the USA ran out of COBOL programmers
James Davenportmasjhd@bath.ac.uk Human Ecosystem? 3 / 17

5. Why am I talking about COBOL here?
Because in 2020 the USA ran out of COBOL programmers (as well
as masks, ventilators etc.).
James Davenportmasjhd@bath.ac.uk Human Ecosystem? 3 / 17

6. Why am I talking about COBOL here?
Because in 2020 the USA ran out of COBOL programmers (as well
as masks, ventilators etc.).
1 New Jersey Gov. Phil Murphy has issued a call for volunteers
who know how to code in the 60-year-old COBOL. “Literally,
we have systems that are 40-plus-years-old”.
James Davenportmasjhd@bath.ac.uk Human Ecosystem? 3 / 17

7. Why am I talking about COBOL here?
Because in 2020 the USA ran out of COBOL programmers (as well
as masks, ventilators etc.).
1 New Jersey Gov. Phil Murphy has issued a call for volunteers
who know how to code in the 60-year-old COBOL. “Literally,
we have systems that are 40-plus-years-old”.
2 Connecticut has also admitted that it’s struggling to process
the large volume of unemployment claims with its“40-year-old
system comprised of a COBOL mainframe and . . . ”
James Davenportmasjhd@bath.ac.uk Human Ecosystem? 3 / 17

8. Why am I talking about COBOL here?
Because in 2020 the USA ran out of COBOL programmers (as well
as masks, ventilators etc.).
1 New Jersey Gov. Phil Murphy has issued a call for volunteers
who know how to code in the 60-year-old COBOL. “Literally,
we have systems that are 40-plus-years-old”.
2 Connecticut has also admitted that it’s struggling to process
the large volume of unemployment claims with its“40-year-old
system comprised of a COBOL mainframe and . . . ”
3 In 2008, then-California Gov. Schwarzenegger wanted to issue
minimum-wage checks to 200,000 state workers, but the
state’s controller said it would need at least six months to
reprogram California’s COBOL-based payroll system to issue
them.
James Davenportmasjhd@bath.ac.uk Human Ecosystem? 3 / 17

9. Why am I talking about COBOL here?
Because in 2020 the USA ran out of COBOL programmers (as well
as masks, ventilators etc.).
1 New Jersey Gov. Phil Murphy has issued a call for volunteers
who know how to code in the 60-year-old COBOL. “Literally,
we have systems that are 40-plus-years-old”.
2 Connecticut has also admitted that it’s struggling to process
the large volume of unemployment claims with its“40-year-old
system comprised of a COBOL mainframe and . . . ”
3 In 2008, then-California Gov. Schwarzenegger wanted to issue
minimum-wage checks to 200,000 state workers, but the
state’s controller said it would need at least six months to
reprogram California’s COBOL-based payroll system to issue
them.
4 A 2018 report by the inspector general for the Social Security
Administration found that the administration maintained more
than “60 million lines of COBOL” (probably not unique lines).
James Davenportmasjhd@bath.ac.uk Human Ecosystem? 3 / 17

10. Why am I talking about COBOL here?
Because in 2020 the USA ran out of COBOL programmers (as well
as masks, ventilators etc.).
1 New Jersey Gov. Phil Murphy has issued a call for volunteers
who know how to code in the 60-year-old COBOL. “Literally,
we have systems that are 40-plus-years-old”.
2 Connecticut has also admitted that it’s struggling to process
the large volume of unemployment claims with its“40-year-old
system comprised of a COBOL mainframe and . . . ”
3 In 2008, then-California Gov. Schwarzenegger wanted to issue
minimum-wage checks to 200,000 state workers, but the
state’s controller said it would need at least six months to
reprogram California’s COBOL-based payroll system to issue
them.
4 A 2018 report by the inspector general for the Social Security
Administration found that the administration maintained more
than “60 million lines of COBOL” (probably not unique lines).
5 A friend got hired back at “>$1000/day” for COBOL maint.
James Davenportmasjhd@bath.ac.uk Human Ecosystem? 3 / 17

11. COBOL (continued)
Over half the states found their COBOL systems couldn’t cope
with the volume of claims. [She20]
James Davenportmasjhd@bath.ac.uk Human Ecosystem? 4 / 17

12. COBOL (continued)
Over half the states found their COBOL systems couldn’t cope
with the volume of claims. [She20]
“IBM is addressing the call for skilled COBOL coders by working in
tandem with the Linux Foundation’s Open Mainframe Project to
create three new initiatives to address the immediate need:
James Davenportmasjhd@bath.ac.uk Human Ecosystem? 4 / 17

13. COBOL (continued)
Over half the states found their COBOL systems couldn’t cope
with the volume of claims. [She20]
“IBM is addressing the call for skilled COBOL coders by working in
tandem with the Linux Foundation’s Open Mainframe Project to
create three new initiatives to address the immediate need:
1 Calling all COBOL Programmers Forum. A new forum
where developers and programmers who would like to
volunteer or are available for hire can post their profiles and
credentials.
James Davenportmasjhd@bath.ac.uk Human Ecosystem? 4 / 17

14. COBOL (continued)
Over half the states found their COBOL systems couldn’t cope
with the volume of claims. [She20]
“IBM is addressing the call for skilled COBOL coders by working in
tandem with the Linux Foundation’s Open Mainframe Project to
create three new initiatives to address the immediate need:
1 Calling all COBOL Programmers Forum. A new forum
where developers and programmers who would like to
volunteer or are available for hire can post their profiles and
credentials.
2 COBOL Technical Forum. A new resource for being actively
monitored by experienced COBOL programmers providing free
advice and expertise.
James Davenportmasjhd@bath.ac.uk Human Ecosystem? 4 / 17

15. COBOL (continued)
Over half the states found their COBOL systems couldn’t cope
with the volume of claims. [She20]
“IBM is addressing the call for skilled COBOL coders by working in
tandem with the Linux Foundation’s Open Mainframe Project to
create three new initiatives to address the immediate need:
1 Calling all COBOL Programmers Forum. A new forum
where developers and programmers who would like to
volunteer or are available for hire can post their profiles and
credentials.
2 COBOL Technical Forum. A new resource for being actively
monitored by experienced COBOL programmers providing free
advice and expertise.
3 Open Source COBOL Training. A brand new open source
course designed to teach COBOL to beginners and refresh
experienced professionals. IBM partnered with the clients and
universities to develop this in-depth course which is available
for free to anyone”.
James Davenportmasjhd@bath.ac.uk Human Ecosystem? 4 / 17

16. But we shouldn’t mock the Americans
James Davenportmasjhd@bath.ac.uk Human Ecosystem? 5 / 17

17. But we shouldn’t mock the Americans
[Fin19] reports a local fiasco.
Ulster Bank’s ageing systems make it impossible for the
lender to routinely charge large corporate customers in the
Republic of Ireland for deposits that run into millions of
euros, according to two people briefed on the issue.
“You wouldn’t believe how hard it is to change”.
Ulster Bank has implemented a manual workaround that
allows it to levy an ad hoc charge on a small number of
the largest depositors.
James Davenportmasjhd@bath.ac.uk Human Ecosystem? 5 / 17

18. But we shouldn’t mock the Americans
[Fin19] reports a local fiasco.
Ulster Bank’s ageing systems make it impossible for the
lender to routinely charge large corporate customers in the
Republic of Ireland for deposits that run into millions of
euros, according to two people briefed on the issue.
“You wouldn’t believe how hard it is to change”.
Ulster Bank has implemented a manual workaround that
allows it to levy an ad hoc charge on a small number of
the largest depositors.
COBOL integers are decimal and unsigned by default
James Davenportmasjhd@bath.ac.uk Human Ecosystem? 5 / 17

19. But we shouldn’t mock the Americans
[Fin19] reports a local fiasco.
Ulster Bank’s ageing systems make it impossible for the
lender to routinely charge large corporate customers in the
Republic of Ireland for deposits that run into millions of
euros, according to two people briefed on the issue.
“You wouldn’t believe how hard it is to change”.
Ulster Bank has implemented a manual workaround that
allows it to levy an ad hoc charge on a small number of
the largest depositors.
COBOL integers are decimal and unsigned by default, and a signed
integer (PIC S99V99) takes more space than an unsigned.
James Davenportmasjhd@bath.ac.uk Human Ecosystem? 5 / 17

20. But we shouldn’t mock the Americans
[Fin19] reports a local fiasco.
Ulster Bank’s ageing systems make it impossible for the
lender to routinely charge large corporate customers in the
Republic of Ireland for deposits that run into millions of
euros, according to two people briefed on the issue.
“You wouldn’t believe how hard it is to change”.
Ulster Bank has implemented a manual workaround that
allows it to levy an ad hoc charge on a small number of
the largest depositors.
COBOL integers are decimal and unsigned by default, and a signed
integer (PIC S99V99) takes more space than an unsigned.
Remember there’s no #include.
Contrary to [Tho19], this isn’t “programmers being unnecessarily
specific”: I’d have written the same code in 1975.
James Davenportmasjhd@bath.ac.uk Human Ecosystem? 5 / 17

21. COBOL: Why so difficult
James Davenportmasjhd@bath.ac.uk Human Ecosystem? 6 / 17

22. COBOL: Why so difficult
After all, similarly-aged languages like FORTRAN don’t have this
problem.
James Davenportmasjhd@bath.ac.uk Human Ecosystem? 6 / 17

23. COBOL: Why so difficult
After all, similarly-aged languages like FORTRAN don’t have this
problem.
1 The FORTRAN ones tend to be in active development (e.g.
Met Office).
James Davenportmasjhd@bath.ac.uk Human Ecosystem? 6 / 17

24. COBOL: Why so difficult
After all, similarly-aged languages like FORTRAN don’t have this
problem.
1 The FORTRAN ones tend to be in active development (e.g.
Met Office).
2 COBOL has no equivalent of #include (and a preprocessor
providing it was my firm’s most successful product in 1975),
which gives a technical debt problem.
James Davenportmasjhd@bath.ac.uk Human Ecosystem? 6 / 17

25. COBOL: Why so difficult
After all, similarly-aged languages like FORTRAN don’t have this
problem.
1 The FORTRAN ones tend to be in active development (e.g.
Met Office).
2 COBOL has no equivalent of #include (and a preprocessor
providing it was my firm’s most successful product in 1975),
which gives a technical debt problem.
3 COBOL has no equivalent of #define, so instead of
#define BATCHSIZE 50000
you have 50000 (and 50001, 49999 etc.) throughout the code.
James Davenportmasjhd@bath.ac.uk Human Ecosystem? 6 / 17

26. COBOL: Why so difficult
After all, similarly-aged languages like FORTRAN don’t have this
problem.
1 The FORTRAN ones tend to be in active development (e.g.
Met Office).
2 COBOL has no equivalent of #include (and a preprocessor
providing it was my firm’s most successful product in 1975),
which gives a technical debt problem.
3 COBOL has no equivalent of #define, so instead of
#define BATCHSIZE 50000
you have 50000 (and 50001, 49999 etc.) throughout the code.
4 Y2K people wrote lots of ad hoc tools
James Davenportmasjhd@bath.ac.uk Human Ecosystem? 6 / 17

27. COBOL: Why so difficult
After all, similarly-aged languages like FORTRAN don’t have this
problem.
1 The FORTRAN ones tend to be in active development (e.g.
Met Office).
2 COBOL has no equivalent of #include (and a preprocessor
providing it was my firm’s most successful product in 1975),
which gives a technical debt problem.
3 COBOL has no equivalent of #define, so instead of
#define BATCHSIZE 50000
you have 50000 (and 50001, 49999 etc.) throughout the code.
4 Y2K people wrote lots of ad hoc tools
 Who knows what my successor in 40 years time will write
about SPARK/cvc-5/Isabelle/. . . , or even about C?
James Davenportmasjhd@bath.ac.uk Human Ecosystem? 6 / 17

28. Technology is not the answer
We’ve tried to migrate using tools to port from mainframe
code to Java. But you end up with Java code which looks
like COBOL, so your Java programmes can’t understand
the code and your mainframe programmers can’t change
it. [Sum22]
James Davenportmasjhd@bath.ac.uk Human Ecosystem? 7 / 17

29. Technology is not the answer
We’ve tried to migrate using tools to port from mainframe
code to Java. But you end up with Java code which looks
like COBOL, so your Java programmes can’t understand
the code and your mainframe programmers can’t change
it. [Sum22]
The problem is the lack of a human ecosystem to understand the
technology.
James Davenportmasjhd@bath.ac.uk Human Ecosystem? 7 / 17

30. And it’s not just the language
A friend (aged ∼72) works for a major bank, maintaining
mission-critical systems.
James Davenportmasjhd@bath.ac.uk Human Ecosystem? 8 / 17

31. And it’s not just the language
A friend (aged ∼72) works for a major bank, maintaining
mission-critical systems.
40 year old system: finally decommissioned.
James Davenportmasjhd@bath.ac.uk Human Ecosystem? 8 / 17

32. And it’s not just the language
A friend (aged ∼72) works for a major bank, maintaining
mission-critical systems.
40 year old system: finally decommissioned.
30 year old system: now runs on Linux hardware, so the
Board aren’t worried any more.
James Davenportmasjhd@bath.ac.uk Human Ecosystem? 8 / 17

33. And it’s not just the language
A friend (aged ∼72) works for a major bank, maintaining
mission-critical systems.
40 year old system: finally decommissioned.
30 year old system: now runs on Linux hardware, so the
Board aren’t worried any more.
20 year old system: I can’t get anyone interested in updating
this.
James Davenportmasjhd@bath.ac.uk Human Ecosystem? 8 / 17

34. And it’s not just the language
A friend (aged ∼72) works for a major bank, maintaining
mission-critical systems.
40 year old system: finally decommissioned.
30 year old system: now runs on Linux hardware, so the
Board aren’t worried any more.
20 year old system: I can’t get anyone interested in updating
this.
 Though I’m the only person who knows how it works,
and there’s no succession plan.
James Davenportmasjhd@bath.ac.uk Human Ecosystem? 8 / 17

35. And it’s not just the language
A friend (aged ∼72) works for a major bank, maintaining
mission-critical systems.
40 year old system: finally decommissioned.
30 year old system: now runs on Linux hardware, so the
Board aren’t worried any more.
20 year old system: I can’t get anyone interested in updating
this.
 Though I’m the only person who knows how it works,
and there’s no succession plan.
James Davenportmasjhd@bath.ac.uk Human Ecosystem? 8 / 17

36. And it’s not just the language
A friend (aged ∼72) works for a major bank, maintaining
mission-critical systems.
40 year old system: finally decommissioned.
30 year old system: now runs on Linux hardware, so the
Board aren’t worried any more.
20 year old system: I can’t get anyone interested in updating
this.
 Though I’m the only person who knows how it works,
and there’s no succession plan.
The fundamental problem isn’t the technology, it’s the
management attitude to software, and the lack of “preventative
maintenance”
James Davenportmasjhd@bath.ac.uk Human Ecosystem? 8 / 17

37. And it’s not just the language
A friend (aged ∼72) works for a major bank, maintaining
mission-critical systems.
40 year old system: finally decommissioned.
30 year old system: now runs on Linux hardware, so the
Board aren’t worried any more.
20 year old system: I can’t get anyone interested in updating
this.
 Though I’m the only person who knows how it works,
and there’s no succession plan.
The fundamental problem isn’t the technology, it’s the
management attitude to software, and the lack of “preventative
maintenance” (which would keep the maintenance team current).
James Davenportmasjhd@bath.ac.uk Human Ecosystem? 8 / 17

38. And it’s not just the language
A friend (aged ∼72) works for a major bank, maintaining
mission-critical systems.
40 year old system: finally decommissioned.
30 year old system: now runs on Linux hardware, so the
Board aren’t worried any more.
20 year old system: I can’t get anyone interested in updating
this.
 Though I’m the only person who knows how it works,
and there’s no succession plan.
The fundamental problem isn’t the technology, it’s the
management attitude to software, and the lack of “preventative
maintenance” (which would keep the maintenance team current).
Also really poor human succession planning.
James Davenportmasjhd@bath.ac.uk Human Ecosystem? 8 / 17

39. Italian Railways [Cim22]
James Davenportmasjhd@bath.ac.uk Human Ecosystem? 9 / 17

40. Italian Railways [Cim22]
Italian railways are migrating away from Relay-based Railway
Interlocking Systems (RRIS).
James Davenportmasjhd@bath.ac.uk Human Ecosystem? 9 / 17

41. Italian Railways [Cim22]
Italian railways are migrating away from Relay-based Railway
Interlocking Systems (RRIS).
1 The factual documentation is on manually drawn paper
diagrams (in a mixed state of preservation).
James Davenportmasjhd@bath.ac.uk Human Ecosystem? 9 / 17

42. Italian Railways [Cim22]
Italian railways are migrating away from Relay-based Railway
Interlocking Systems (RRIS).
1 The factual documentation is on manually drawn paper
diagrams (in a mixed state of preservation).
2 The intellectual documentation (“why” etc.) is in informal
documents and engineers’ heads.
James Davenportmasjhd@bath.ac.uk Human Ecosystem? 9 / 17

43. Italian Railways [Cim22]
Italian railways are migrating away from Relay-based Railway
Interlocking Systems (RRIS).
1 The factual documentation is on manually drawn paper
diagrams (in a mixed state of preservation).
2 The intellectual documentation (“why” etc.) is in informal
documents and engineers’ heads.
 “Moreover, the work on these documents requires a strong
legacy domain knowledge which is vanishing in these days”
[ABC+20]
James Davenportmasjhd@bath.ac.uk Human Ecosystem? 9 / 17

44. Italian Railways [Cim22]
Italian railways are migrating away from Relay-based Railway
Interlocking Systems (RRIS).
1 The factual documentation is on manually drawn paper
diagrams (in a mixed state of preservation).
2 The intellectual documentation (“why” etc.) is in informal
documents and engineers’ heads.
 “Moreover, the work on these documents requires a strong
legacy domain knowledge which is vanishing in these days”
[ABC+20]
B 1 is “solved” via scanning, editing and verifying [ABC+22]
James Davenportmasjhd@bath.ac.uk Human Ecosystem? 9 / 17

45. Italian Railways [Cim22]
Italian railways are migrating away from Relay-based Railway
Interlocking Systems (RRIS).
1 The factual documentation is on manually drawn paper
diagrams (in a mixed state of preservation).
2 The intellectual documentation (“why” etc.) is in informal
documents and engineers’ heads.
 “Moreover, the work on these documents requires a strong
legacy domain knowledge which is vanishing in these days”
[ABC+20]
B 1 is “solved” via scanning, editing and verifying [ABC+22]
A 2 is solved via capture with Controlled Natural Language
[ABC+20]
James Davenportmasjhd@bath.ac.uk Human Ecosystem? 9 / 17

46. Italian Railways Workflow [ABC+
20, Figure 1]
James Davenportmasjhd@bath.ac.uk Human Ecosystem? 10 / 17

47. Italian Railways Workflow [ABC+
20, Figure 1]
Hopefully our successors will not be building anything this complex
to understand our artefacts, but how sure can we be?
James Davenportmasjhd@bath.ac.uk Human Ecosystem? 10 / 17

48. Italian Railways Workflow [ABC+
20, Figure 1]
Hopefully our successors will not be building anything this complex
to understand our artefacts, but how sure can we be?
B We can reasonably hope that our artefacts are fully formal.
James Davenportmasjhd@bath.ac.uk Human Ecosystem? 10 / 17

49. Italian Railways Workflow [ABC+
20, Figure 1]
Hopefully our successors will not be building anything this complex
to understand our artefacts, but how sure can we be?
B We can reasonably hope that our artefacts are fully formal.
A But “strong legacy domain knowledge”?
James Davenportmasjhd@bath.ac.uk Human Ecosystem? 10 / 17

50. Paris Métro Line 14 [Déh22]
James Davenportmasjhd@bath.ac.uk Human Ecosystem? 11 / 17

51. Paris Métro Line 14 [Déh22]
1998 Opened; fully automatic; critical software verified by
Atelier B. major showcase.
James Davenportmasjhd@bath.ac.uk Human Ecosystem? 11 / 17

52. Paris Métro Line 14 [Déh22]
1998 Opened; fully automatic; critical software verified by
Atelier B. major showcase.
 This software (rather than the construction process)
was signed off, with no change process [Déh17,
Minute 14:30].
James Davenportmasjhd@bath.ac.uk Human Ecosystem? 11 / 17

53. Paris Métro Line 14 [Déh22]
1998 Opened; fully automatic; critical software verified by
Atelier B. major showcase.
 This software (rather than the construction process)
was signed off, with no change process [Déh17,
Minute 14:30].
2003,2007 Extensions opened (but already in the verified
software).
James Davenportmasjhd@bath.ac.uk Human Ecosystem? 11 / 17

54. Paris Métro Line 14 [Déh22]
1998 Opened; fully automatic; critical software verified by
Atelier B. major showcase.
 This software (rather than the construction process)
was signed off, with no change process [Déh17,
Minute 14:30].
2003,2007 Extensions opened (but already in the verified
software).
2010s Planning for new extensions, not in software.
James Davenportmasjhd@bath.ac.uk Human Ecosystem? 11 / 17

55. Paris Métro Line 14 [Déh22]
1998 Opened; fully automatic; critical software verified by
Atelier B. major showcase.
 This software (rather than the construction process)
was signed off, with no change process [Déh17,
Minute 14:30].
2003,2007 Extensions opened (but already in the verified
software).
2010s Planning for new extensions, not in software.
 Atelier B only runs on Sun workstations, ported to
Linux (but not necessarily 100% identical, and
previous software didn’t verify out-of-the-box).
James Davenportmasjhd@bath.ac.uk Human Ecosystem? 11 / 17

56. Paris Métro Line 14 [Déh22]
1998 Opened; fully automatic; critical software verified by
Atelier B. major showcase.
 This software (rather than the construction process)
was signed off, with no change process [Déh17,
Minute 14:30].
2003,2007 Extensions opened (but already in the verified
software).
2010s Planning for new extensions, not in software.
 Atelier B only runs on Sun workstations, ported to
Linux (but not necessarily 100% identical, and
previous software didn’t verify out-of-the-box).
2020 New extension, with new trains running 2× faster.
James Davenportmasjhd@bath.ac.uk Human Ecosystem? 11 / 17

57. Paris Métro Line 14 [Déh22]
1998 Opened; fully automatic; critical software verified by
Atelier B. major showcase.
 This software (rather than the construction process)
was signed off, with no change process [Déh17,
Minute 14:30].
2003,2007 Extensions opened (but already in the verified
software).
2010s Planning for new extensions, not in software.
 Atelier B only runs on Sun workstations, ported to
Linux (but not necessarily 100% identical, and
previous software didn’t verify out-of-the-box).
2020 New extension, with new trains running 2× faster.
 The new trains were 8 carriages, not 6, so not every
door opens at every station; significant modification.
James Davenportmasjhd@bath.ac.uk Human Ecosystem? 11 / 17

58. Paris Métro Line 14 [Déh22]
1998 Opened; fully automatic; critical software verified by
Atelier B. major showcase.
 This software (rather than the construction process)
was signed off, with no change process [Déh17,
Minute 14:30].
2003,2007 Extensions opened (but already in the verified
software).
2010s Planning for new extensions, not in software.
 Atelier B only runs on Sun workstations, ported to
Linux (but not necessarily 100% identical, and
previous software didn’t verify out-of-the-box).
2020 New extension, with new trains running 2× faster.
 The new trains were 8 carriages, not 6, so not every
door opens at every station; significant modification.
q
But it’s running formally verified GoA4 [Cue20].
James Davenportmasjhd@bath.ac.uk Human Ecosystem? 11 / 17

59. Questions
James Davenportmasjhd@bath.ac.uk Human Ecosystem? 12 / 17

60. Questions
1 Cobol: Do you keep programming in a sufficiently similar
language?
James Davenportmasjhd@bath.ac.uk Human Ecosystem? 12 / 17

61. Questions
1 Cobol: Do you keep programming in a sufficiently similar
language?
2 Atelier B: Is your proof infrastructure still maintained?
James Davenportmasjhd@bath.ac.uk Human Ecosystem? 12 / 17

62. Questions
1 Cobol: Do you keep programming in a sufficiently similar
language?
2 Atelier B: Is your proof infrastructure still maintained?
3 Ligne 14: Just because a theorem verifies automatically today
doesn’t mean it will verify automatically in 20 years time. Is it
worth/possible recording some major steps of the automatic
proof, rather than “relying on upwards compatibility”
James Davenportmasjhd@bath.ac.uk Human Ecosystem? 12 / 17

63. Questions
1 Cobol: Do you keep programming in a sufficiently similar
language?
2 Atelier B: Is your proof infrastructure still maintained?
3 Ligne 14: Just because a theorem verifies automatically today
doesn’t mean it will verify automatically in 20 years time. Is it
worth/possible recording some major steps of the automatic
proof, rather than “relying on upwards compatibility”
 This may be more serious as more machine learning
(sledgehammer etc.) is used in proof systems.
James Davenportmasjhd@bath.ac.uk Human Ecosystem? 12 / 17

64. Questions
1 Cobol: Do you keep programming in a sufficiently similar
language?
2 Atelier B: Is your proof infrastructure still maintained?
3 Ligne 14: Just because a theorem verifies automatically today
doesn’t mean it will verify automatically in 20 years time. Is it
worth/possible recording some major steps of the automatic
proof, rather than “relying on upwards compatibility”
 This may be more serious as more machine learning
(sledgehammer etc.) is used in proof systems.
4 Italy: Are you reliant on “strong legacy domain knowledge”?
James Davenportmasjhd@bath.ac.uk Human Ecosystem? 12 / 17

65. Questions
1 Cobol: Do you keep programming in a sufficiently similar
language?
2 Atelier B: Is your proof infrastructure still maintained?
3 Ligne 14: Just because a theorem verifies automatically today
doesn’t mean it will verify automatically in 20 years time. Is it
worth/possible recording some major steps of the automatic
proof, rather than “relying on upwards compatibility”
 This may be more serious as more machine learning
(sledgehammer etc.) is used in proof systems.
4 Italy: Are you reliant on “strong legacy domain knowledge”?
 “The Empire can’t maintain anything” — Hober Mallow
[Asi44].
James Davenportmasjhd@bath.ac.uk Human Ecosystem? 12 / 17

66. Bibliography
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E. Ábrahám, B. Becker, A. Bigatti, B. Buchberger, A. Cimatti,
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SC2: Satisfiability Checking meets Symbolic Computation
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A. Amendola, A. Becchi, R. Cavada, A. Cimatti, A. Griggio,
G. Scaglione, A. Susi, A. Tacchella, and M. Tessi.
A model-based approach to the design, verification and
deployment of railway interlocking system.
In Proceedings International Symposium on Leveraging
Applications of Formal Methods ISOLA 2020, pages 240–254,
2020.
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67. Bibliography
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A. Amendola, A. Becchi, R. Cavada, A. Cimatti, A. Ferrando,
L. Pilati, G. Scaglione, A. Tacchella, and M. Zamboni.
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Interlocking Systems.
Tools and Algorithms for the Construction and Analysis of
Systems TACAS 2022, pages 125–142, 2022.
I. Asimov.
The Big and the Little [reprinted as “Merchant Princes” in
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Astounding, 33:7–54, 1944.
A. Cimatti.
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Personal Communication at Dagstuhl February 2022, 2022.
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68. Bibliography
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O. Cuenca.
Paris inaugurates Line 14 extension.
https://www.railjournal.com/passenger/metros/
paris-inaugurates-line-14-extension/, 2020.
D. Déharbe.
Talk at SCSC Summer School.
https://vimeo.com/showcase/5271198, 2017.
D. Déharbe.
Évolution de la ligne 14.
Personal Communication 11 August, 2022.
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69. Bibliography
IV
Financial Times.
Ulster Bank’s computer says no to negative rates.
https://www.ft.com/content/
ff12856a-e07d-11e9-9743-db5a370481bc, 2019.
E. Shein.
COBOL programmers are in demand to fight the coronavirus
pandemic.
https://www.techrepublic.com/article/
cobol-programmers-are-in-demand-to-fight-the-coronaviru
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70. Bibliography
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S. Sumner.
Computing gathered a group of UK-based IT leaders together
to discuss their legacy concerns, including security, skills and
cost issues.
https://www.computing.co.uk/news/4057289/
cios-discuss-legacy-issues-dont-write-mainframe,
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M. Thomas.
Ethics, old software and negative interest rates.
Letter to Financial Times 4 October, 2019.
James Davenportmasjhd@bath.ac.uk Human Ecosystem? 17 / 17